PEL: Support resolution property

Support resolution property to add callouts

Tested: Created new PEL using busctl and checked for the property to
see if the value is updated. The error log daemon was restarted and the
property is checked again to make sure the value is restored.

Verified serialization of new error log by recreating it on a old code
version to make sure logs are created w/o the new property and the
daemon did not crash.

Result:
root@rainier:~# busctl get-property xyz.openbmc_project.Logging \
 /xyz/openbmc_project/logging/entry/1 xyz.openbmc_project.Logging.\
 Entry Resolution
s "1. Priority: High, Procedure: BMCSP02\n2. Priority: Medium, PN: \
SVCDOCS\n"

Test with location Code:
root@p10bmc:~# busctl get-property xyz.openbmc_project.Logging \
/xyz/openbmc_project/logging/entry/3 xyz.openbmc_project.Logging.Entry \
Resolution
s "1. Location Code: U78DA.ND0.1234567-P0, Priority: Medium, PN: SVCDOCS\n2. \
Priority: Low, Procedure: BMCSP02\n"

Signed-off-by: Vijay Lobo <vijaylobo@gmail.com>
Change-Id: I44eebbf794efeb8e752fff98de7c638c927982cd
diff --git a/elog_entry.cpp b/elog_entry.cpp
index f0b3e45..1bd70c2 100644
--- a/elog_entry.cpp
+++ b/elog_entry.cpp
@@ -56,6 +56,21 @@
     return current;
 }
 
+std::string Entry::resolution(std::string value)
+{
+    auto current =
+        sdbusplus::xyz::openbmc_project::Logging::server::Entry::resolution();
+    if (value != current)
+    {
+        current =
+            sdbusplus::xyz::openbmc_project::Logging::server::Entry::resolution(
+                value);
+        serialize(*this);
+    }
+
+    return current;
+}
+
 sdbusplus::message::unix_fd Entry::getEntry()
 {
     FILE* fp = fopen(path().c_str(), "rb");