Enable Lint Rules: struct-tag & unexported-return

[FlamingSaint]

Which problem is this PR solving?

• Partial Fix for Enable more revive linter rules #5506

Description of the changes

• Enabled struct-tag & unexported-return in revive linter
• Only use tags on exported fields
• Converted exported function to have an exported return type

How was this change tested?

• make lint make test

Checklist

• I have read https://github.com/jaegertracing/jaeger/blob/master/CONTRIBUTING_GUIDELINES.md
• I have signed all commits
• I have added unit tests for the new functionality
• I have run lint and test steps successfully
  • for jaeger: make lint test
  • for jaeger-ui: yarn lint and yarn test

[codecov]

Codecov Report

Attention: Patch coverage is 93.75000% with 1 line in your changes missing coverage. Please review.

Project coverage is 96.21%. Comparing base (6b95711) to head (8e19489).

Files	Patch %	Lines
plugin/storage/grpc/shared/grpc_client.go	93.75%	1 Missing ⚠️

Additional details and impacted files

@@             Coverage Diff             @@
##             main    #5533       +/-   ##
===========================================
+ Coverage   54.25%   96.21%   +41.95%     
===========================================
  Files         161      327      +166     
  Lines        8366    16007     +7641     
===========================================
+ Hits         4539    15401    +10862     
+ Misses       3381      431     -2950     
+ Partials      446      175      -271     

Flag	Coverage Δ
badger_v1	8.05% <0.00%> (ø)
badger_v2	1.93% <0.00%> (ø)
cassandra-3.x-v1	16.45% <0.00%> (ø)
cassandra-3.x-v2	1.85% <0.00%> (ø)
cassandra-4.x-v1	16.45% <0.00%> (ø)
cassandra-4.x-v2	1.85% <0.00%> (ø)
elasticsearch-7-v1	18.89% <0.00%> (ø)
elasticsearch-8-v1	19.07% <0.00%> (-0.02%)	⬇️
elasticsearch-8-v2	19.07% <0.00%> (ø)
grpc_v1	9.48% <68.75%> (+0.01%)	⬆️
grpc_v2	7.53% <0.00%> (ø)
kafka	9.77% <0.00%> (ø)
opensearch-1-v1	18.94% <0.00%> (+0.01%)	⬆️
opensearch-2-v1	18.94% <0.00%> (ø)
opensearch-2-v2	18.93% <0.00%> (-0.02%)	⬇️
unittests	94.09% <87.50%> (?)

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