Add implementation of otlploggrpc configuration

[XSAM]

part of #5056

Most of the codes are copied from otlploghttp.

I will try to make internal/conf as a shared go template file so otlploghttp can use a shared setting struct with otlploggrpc in the following PRs.

[codecov]

Codecov Report

Attention: Patch coverage is 93.10345% with 14 lines in your changes missing coverage. Please review.

Project coverage is 84.8%. Comparing base (722fbae) to head (e94ea96).

Additional details and impacted files

@@           Coverage Diff           @@
##            main   #5383     +/-   ##
=======================================
+ Coverage   84.6%   84.8%   +0.2%     
=======================================
  Files        268     268             
  Lines      17852   18037    +185     
=======================================
+ Hits       15111   15311    +200     
+ Misses      2428    2407     -21     
- Partials     313     319      +6     

Files	Coverage Δ
exporters/otlp/otlplog/otlploggrpc/config.go	93.4% <93.1%> (+93.4%)	⬆️

... and 2 files with indirect coverage changes

[pellared]

I will try to make this as a shared go template file so otlploghttp can use a shared logic with otlploggrpc in the following PRs.

Keep in mind that I am not sure if this would be worth the effort given these configs are not 1:1.

[XSAM]

Two things I think we can make as a shared template in the following PRs:

• internal/conf
• TLS certificate methods