implement grpc health check service

[mikemrm]

This implements the standard grpc health check service methods.

Extending each underlying service library to include a HealthCheck method called by the GRPC HealthService Check.

[codecov-commenter]

Codecov Report

Attention: Patch coverage is 0% with 242 lines in your changes missing coverage. Please review.

Please upload report for BASE (main@cc9f3d3). Learn more about missing BASE report.

Files with missing lines	Patch %	Lines
internal/server/server.go	0.00%	79 Missing ⚠️
internal/accesstoken/tokensource.go	0.00%	42 Missing ⚠️
internal/permissions/client.go	0.00%	39 Missing ⚠️
internal/jwt/validator.go	0.00%	31 Missing ⚠️
internal/server/health.go	0.00%	31 Missing ⚠️
internal/eventsx/publisher.go	0.00%	19 Missing ⚠️
internal/server/config.go	0.00%	1 Missing ⚠️

Additional details and impacted files

@@           Coverage Diff           @@
##             main     #105   +/-   ##
=======================================
  Coverage        ?   32.58%           
=======================================
  Files           ?       29           
  Lines           ?     1955           
  Branches        ?        0           
=======================================
  Hits            ?      637           
  Misses          ?     1300           
  Partials        ?       18           

Flag	Coverage Δ
unittests	32.58% <0.00%> (?)

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