SEL capture support

[mattcburns]

Description

This PR adds in the newly added System Event Log (SEL) capture support added in bmclib.

Note: This updates a previous PR I pulled to remove some duplicate code in my implementation.

How Has This Been Tested?

Tested against a couple of different servers for both opinionated structured and the raw capture methods with success.

How are existing users impacted? What migration steps/scripts do we need?

New methods are available to expose the SEL capture functionality added in bmclib. Two new gRPC endpoints are available:

Diagnostic/GetSystemEventLog - returns an opinionated format of the SEL consisting of a list of id,timestamp,description,message
Diagnostic/GetSystemEventLogRaw - returns a raw dump of the SEL, so that the requestor may parse as they please.

Checklist:

I have:

• updated the documentation and/or roadmap (if required)
• added unit or e2e tests
• provided instructions on how to upgrade

[codecov]

Codecov Report

Attention: 37 lines in your changes are missing coverage. Please review.

Comparison is base (c15e8a7) 81.87% compared to head (6c3d65c) 76.75%.

Files	Patch %	Lines
grpc/rpc/diagnostic.go	27.45%	37 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main     #155      +/-   ##
==========================================
- Coverage   81.87%   76.75%   -5.13%     
==========================================
  Files           9        9              
  Lines         491      542      +51     
==========================================
+ Hits          402      416      +14     
- Misses         75      112      +37     
  Partials       14       14              

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