entry: use map for metadata in ctor

Transition the entry constructor to use the `map<string,string>`
rather than the `vector<string>`.

Tested: UTs pass and daemon still creates logs.

Signed-off-by: Patrick Williams <patrick@stwcx.xyz>
Change-Id: Icf3ead163cc99a1498734d33335fb6da52e6c98c
diff --git a/lib/lg2_commit.hpp b/lib/lg2_commit.hpp
index db6bab0..1ab4302 100644
--- a/lib/lg2_commit.hpp
+++ b/lib/lg2_commit.hpp
@@ -17,6 +17,7 @@
  *  @return A tuple containing the message, level, and additional data.
  */
 auto extractEvent(sdbusplus::exception::generated_event_base&&)
-    -> std::tuple<std::string, Entry::Level, std::vector<std::string>>;
+    -> std::tuple<std::string, Entry::Level,
+                  std::map<std::string, std::string>>;
 
 } // namespace lg2::details