feature: gRPC instrument

[jiekun]

Added

• gRPC instrument.

[codecov]

Codecov Report

Attention: 20 lines in your changes are missing coverage. Please review.

Comparison is base (b512e87) 89.70% compared to head (c826e6d) 87.61%.

Files	Patch %	Lines
metrics/grpc/grpc.go	86.57%	15 Missing and 5 partials ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##           master       #4      +/-   ##
==========================================
- Coverage   89.70%   87.61%   -2.10%     
==========================================
  Files           3        4       +1     
  Lines          68      218     +150     
==========================================
+ Hits           61      191     +130     
- Misses          5       20      +15     
- Partials        2        7       +5     

☔ View full report in Codecov by Sentry.
📢 Have feedback on the report? Share it here.