x/staking: gRPC query Service

[sahith-narahari]

Description

Ref: #5921

---

Before we can merge this PR, please make sure that all the following items have been
checked off. If any of the checklist items are not applicable, please leave them but
write a little note why.

• Targeted PR against correct branch (see CONTRIBUTING.md)
• Linked to Github issue with discussion and accepted design OR link to spec that describes this work.
• Code follows the module structure standards.
• Wrote unit and integration tests
• Updated relevant documentation (docs/) or specification (x/<module>/spec/)
• Added relevant godoc comments.
• Added a relevant changelog entry to the Unreleased section in CHANGELOG.md
• Re-reviewed Files changed in the Github PR explorer

[codecov]

Codecov Report

Merging #6490 into master will increase coverage by 0.18%.
The diff coverage is 70.86%.

@@            Coverage Diff             @@
##           master    #6490      +/-   ##
==========================================
+ Coverage   58.46%   58.65%   +0.18%     
==========================================
  Files         511      512       +1     
  Lines       31047    31280     +233     
==========================================
+ Hits        18151    18346     +195     
- Misses      11543    11546       +3     
- Partials     1353     1388      +35     

[lgtm-com]

This pull request introduces 3 alerts when merging bc3775f into 06d7dbe - view on LGTM.com

new alerts:

• 3 for Useless assignment to local variable

[lgtm-com]

This pull request introduces 9 alerts when merging e4738c7 into cb6c552 - view on LGTM.com

new alerts:

• 9 for Useless assignment to local variable

[lgtm-com]

This pull request introduces 3 alerts when merging a485a85 into 51c35f4 - view on LGTM.com

new alerts:

• 3 for Useless assignment to local variable

[aaronc]

I notice gogoproto.nullable = false is used a lot. Is this really needed? I'd rather minimize the usage of those annotations to things needed for backwards golang API compatibility. Is it to reduce nil checks?

[sahith-narahari]

I notice gogoproto.nullable = false is used a lot. Is this really needed? I'd rather minimize the usage of those annotations to things needed for backwards golang API compatibility. Is it to reduce nil checks?

The main reason was to avoid dealing with nil data, but agree gogoproto extension usage should be minimised. Will ensure to keep it in mind for future work

[aaronc]

@sahith-narahari thanks. I think it's okay to leave it for now. I understand it would be a bigger refactor.