Consider adding EventArgs infrastructure unit tests

During investigation of https://github.com/dotnet/msbuild/issues/9098 I identified few unit tests missing coverage:

a) binlog end to end test
- prepare small test solution of 2 projects to assure out of proc build
- built it with /v:diag /bl /m and capture console
- replay bin log and capture output
- compare those two captures, they shall be identical
- rinse and repeat for /flp:v=diag /bl /m /tl and compare resulted file loggers outputs

b) events delivery verification
- prepare small test solution of 2 projects to assure out of proc build
- use small catch-em-all loggers which would capture all events into memory (I think existing `MockLogger` can be used here)
- assert some subset of messages from captured list

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@AR-May - optionally it could be part of #9098 fix