Implement Liquid Leak Detector

Implement liquid leak detector based on design
https://gerrit.openbmc.org/c/openbmc/docs/+/73152.

Related PRs:
https://gerrit.openbmc.org/c/openbmc/phosphor-dbus-interfaces/+/73151
https://gerrit.openbmc.org/c/openbmc/phosphor-dbus-interfaces/+/73707
https://gerrit.openbmc.org/c/openbmc/sdbusplus/+/75461
https://gerrit.openbmc.org/c/openbmc/phosphor-dbus-interfaces/+/75999

Tested:
```
>> busctl tree xyz.openbmc_project.LeakDetector
└─ /xyz
  └─ /xyz/openbmc_project
    └─ /xyz/openbmc_project/state
      └─ /xyz/openbmc_project/state/leak
        └─ /xyz/openbmc_project/state/leak/detector
          ├─ /xyz/openbmc_project/state/leak/detector/TrayDetector1
          └─ /xyz/openbmc_project/state/leak/detector/TrayDetector2

>> echo pull-up > /sys/devices/platform/gpio-sim.0/gpiochip2/sim_gpio0/pull

>> curl -k -H "X-Auth-Token: $token" -X GET https://${bmc}/redfish/v1/Systems/system/LogServices/EventLog/Entries
{
  "@odata.id": "/redfish/v1/Systems/system/LogServices/EventLog/Entries",
  "@odata.type": "#LogEntryCollection.LogEntryCollection",
  "Description": "Collection of System Event Log Entries",
  "Members": [
  	...
    {
      "@odata.id": "/redfish/v1/Systems/system/LogServices/EventLog/Entries/2",
      "@odata.type": "#LogEntry.v1_9_0.LogEntry",
      "AdditionalDataURI": "/redfish/v1/Systems/system/LogServices/EventLog/Entries/2/attachment",
      "Created": "2024-05-10T06:40:30.423+00:00",
      "EntryType": "Event",
      "Id": "2",
      "Message": "xyz.openbmc_project.State.Leak.Detector.LeakDetectedWarning",
      "Modified": "2024-05-10T06:40:30.423+00:00",
      "Name": "System Event Log Entry",
      "Resolved": false,
      "Severity": "Warning"
    }
  ],
  "Members@odata.count": 2,
  "Name": "System Event Log Entries"
}

>> echo pull-down > /sys/devices/platform/gpio-sim.0/gpiochip2/sim_gpio0/pull

>> curl -k -H "X-Auth-Token: $token" -X GET https://${bmc}/redfish/v1/Systems/system/LogServices/EventLog/Entries
{
  "@odata.id": "/redfish/v1/Systems/system/LogServices/EventLog/Entries",
  "@odata.type": "#LogEntryCollection.LogEntryCollection",
  "Description": "Collection of System Event Log Entries",
  "Members": [
	...
    {
      "@odata.id": "/redfish/v1/Systems/system/LogServices/EventLog/Entries/2",
      "@odata.type": "#LogEntry.v1_9_0.LogEntry",
      "AdditionalDataURI": "/redfish/v1/Systems/system/LogServices/EventLog/Entries/2/attachment",
      "Created": "2024-05-10T06:40:30.423+00:00",
      "EntryType": "Event",
      "Id": "2",
      "Message": "xyz.openbmc_project.State.Leak.Detector.LeakDetectedWarning",
      "Modified": "2024-05-10T06:42:23.989+00:00",
      "Name": "System Event Log Entry",
      "Resolved": true,
      "Severity": "Warning"
    },
    {
      "@odata.id": "/redfish/v1/Systems/system/LogServices/EventLog/Entries/3",
      "@odata.type": "#LogEntry.v1_9_0.LogEntry",
      "AdditionalDataURI": "/redfish/v1/Systems/system/LogServices/EventLog/Entries/3/attachment",
      "Created": "2024-05-10T06:42:24.024+00:00",
      "EntryType": "Event",
      "Id": "3",
      "Message": "xyz.openbmc_project.State.Leak.Detector.LeakDetectedNormal",
      "Modified": "2024-05-10T06:42:24.024+00:00",
      "Name": "System Event Log Entry",
      "Resolved": false,
      "Severity": "OK"
    }
  ],
  "Members@odata.count": 3,
  "Name": "System Event Log Entries"
}
```

Change-Id: Id6981deb314ca6852c5e31b932b28e601c2f3976
Signed-off-by: Jagpal Singh Gill <paligill@gmail.com>
diff --git a/src/leakdetector/LeakEvents.cpp b/src/leakdetector/LeakEvents.cpp
new file mode 100644
index 0000000..e3755a7
--- /dev/null
+++ b/src/leakdetector/LeakEvents.cpp
@@ -0,0 +1,64 @@
+#include "LeakEvents.hpp"
+
+#include "LeakGPIODetector.hpp"
+
+#include <phosphor-logging/commit.hpp>
+#include <phosphor-logging/lg2.hpp>
+#include <sdbusplus/async.hpp>
+#include <sdbusplus/message/native_types.hpp>
+#include <xyz/openbmc_project/State/Leak/Detector/event.hpp>
+
+#include <tuple>
+
+PHOSPHOR_LOG2_USING;
+
+namespace leak
+{
+
+auto Events::generateLeakEvent(sdbusplus::message::object_path detectorPath,
+                               DetectorStateIntf::DetectorState state,
+                               config::DetectorLevel level)
+    -> sdbusplus::async::task<>
+{
+    auto eventName = std::make_tuple(detectorPath.str, level);
+
+    // NOLINTNEXTLINE(clang-analyzer-core.uninitialized.Branch)
+    if (state == DetectorStateIntf::DetectorState::Normal)
+    {
+        auto pendingEvent = pendingEvents.find(eventName);
+        if (pendingEvent != pendingEvents.end())
+        {
+            co_await lg2::resolve(ctx, pendingEvent->second);
+
+            using DetectorNormal = sdbusplus::event::xyz::openbmc_project::
+                state::leak::Detector::LeakDetectedNormal;
+            co_await lg2::commit(ctx,
+                                 DetectorNormal("DETECTOR_NAME", detectorPath));
+
+            pendingEvents.erase(eventName);
+        }
+        co_return;
+    }
+
+    namespace error_intf =
+        sdbusplus::error::xyz::openbmc_project::state::leak::Detector;
+    sdbusplus::message::object_path eventPath{};
+
+    if (level == config::DetectorLevel::critical)
+    {
+        eventPath = co_await lg2::commit(
+            ctx,
+            error_intf::LeakDetectedCritical("DETECTOR_NAME", detectorPath));
+        error("Critical leak detected for {PATH}", "PATH", detectorPath);
+    }
+    else
+    {
+        eventPath = co_await lg2::commit(
+            ctx,
+            error_intf::LeakDetectedWarning("DETECTOR_NAME", detectorPath));
+        warning("Warning leak detected for {PATH}", "PATH", detectorPath);
+    }
+    pendingEvents[eventName] = eventPath;
+}
+
+} // namespace leak