Move QueryTx functions to x/auth/tx

[amaury1093]

Description

closes: #8680
closes: #8681

It was confusing that the gRPC handler GetTxsEvent was in x/auth/tx, whereas the logic QueryTxsByEvents was in x/auth/client (same for querying tx by hash). I propose to put them together in x/auth/tx.

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(on a related note: I find the 2 packages x/auth/client and x/auth/tx too similar. For example, x/auth/client exports the SignTx function, which could totally be in x/auth/tx. Maybe merging them would make things cleaner?)

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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
• Review Codecov Report in the comment section below once CI passes

[codecov]

Codecov Report

Merging #8734 (da84657) into master (5f2b90c) will increase coverage by 0.06%.
The diff coverage is 70.00%.

@@            Coverage Diff             @@
##           master    #8734      +/-   ##
==========================================
+ Coverage   61.38%   61.45%   +0.06%     
==========================================
  Files         673      673              
  Lines       38337    38306      -31     
==========================================
+ Hits        23535    23541       +6     
+ Misses      12334    12285      -49     
- Partials     2468     2480      +12     

Impacted Files	Coverage Δ
x/auth/tx/query.go	47.54% <ø> (ø)
x/staking/client/rest/utils.go	0.00% <0.00%> (ø)
x/auth/client/cli/query.go	38.70% <50.00%> (ø)
x/auth/tx/service.go	69.35% <71.42%> (-2.69%)	⬇️
x/auth/client/rest/query.go	38.83% <100.00%> (ø)
x/gov/client/utils/query.go	25.72% <100.00%> (ø)
x/auth/tx/builder.go	76.37% <0.00%> (+0.78%)	⬆️

[amaury1093]

i forgot to add a changelog entry. it's an API-breaking change, so it deserves one. #8736 (comment)

[robert-zaremba]

(on a related note: I find the 2 packages x/auth/client and x/auth/tx too similar. For example, x/auth/client exports the SignTx function, which could totally be in x/auth/tx. Maybe merging them would make things cleaner?)

x/auth needs a big refactor. I started it few months ago, but it took more then expected and didn't finish. Major problem is that other packages (anything not in x/...) modules depends on x/auth.

[alessio]

Major problem is that other packages (anything not in x/...) modules depends on x/auth.

It's a major one indeed. Nothing outside x/ must depend on anything under the x/ tree