log-manager: enable non-standard path for local tests

Enable the log-manager to be launched with a path other than
`/var/phosphor-logging` to allow it to be ran on a development system
for test purposes.  This required some refactoring throughout as to
how paths were handled.

Tested:

After running tests, `/tmp/phosphor-logging` is populated with
entries.  Launching `./builddir/phosphor-log-manager
/tmp/phosphor-logging`, the log-manager will have the entries on
dbus:

```
$ busctl --user tree xyz.openbmc_project.Logging
└─ /xyz
  └─ /xyz/openbmc_project
    └─ /xyz/openbmc_project/logging
      ├─ /xyz/openbmc_project/logging/entry
      │ ├─ /xyz/openbmc_project/logging/entry/100
      │ ├─ /xyz/openbmc_project/logging/entry/101
      │ ├─ /xyz/openbmc_project/logging/entry/102
      │ ├─ /xyz/openbmc_project/logging/entry/103
```

Signed-off-by: Patrick Williams <patrick@stwcx.xyz>
Change-Id: I84968edeed0dcf73aaf8bb653060b6d3400b9b7b
diff --git a/elog_serialize.hpp b/elog_serialize.hpp
index 38ff424..29791b2 100644
--- a/elog_serialize.hpp
+++ b/elog_serialize.hpp
@@ -3,6 +3,7 @@
 #include "config.h"
 
 #include "elog_entry.hpp"
+#include "paths.hpp"
 
 #include <filesystem>
 #include <string>
@@ -22,7 +23,7 @@
  *  @return fs::path - pathname of persisted error file
  */
 fs::path serialize(const Entry& e,
-                   const fs::path& dir = fs::path(ERRLOG_PERSIST_PATH));
+                   const fs::path& dir = fs::path(paths::error()));
 
 /** @brief Deserialze a persisted error into a d-bus object
  *  @param[in] path - pathname of persisted error file
@@ -38,8 +39,8 @@
  *                   be placed.
  *  @return fs::path - pathname of persisted error file
  */
-fs::path getEntrySerializePath(
-    uint32_t id, const fs::path& dir = fs::path(ERRLOG_PERSIST_PATH));
+fs::path getEntrySerializePath(uint32_t id,
+                               const fs::path& dir = fs::path(paths::error()));
 
 } // namespace logging
 } // namespace phosphor