refactor: extract MockTendermintRPC to testutil/cli

[julienrbrt]

Description

ref: #13692 (comment)

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• confirmed the correct type prefix in the PR title
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[codecov]

Codecov Report

Merging #13749 (5e12ec9) into main (779c0ac) will increase coverage by 0.09%.
The diff coverage is n/a.

Additional details and impacted files

@@            Coverage Diff             @@
##             main   #13749      +/-   ##
==========================================
+ Coverage   56.05%   56.15%   +0.09%     
==========================================
  Files         646      655       +9     
  Lines       55790    56195     +405     
==========================================
+ Hits        31271    31554     +283     
- Misses      21979    22065      +86     
- Partials     2540     2576      +36     

Impacted Files	Coverage Δ
crypto/keys/internal/ecdsa/privkey.go	81.13% <0.00%> (-1.89%)	⬇️
x/staking/simulation/operations.go	74.54% <0.00%> (-1.38%)	⬇️
tx/textual/valuerenderer/timestamp.go	89.28% <0.00%> (ø)
tx/textual/valuerenderer/duration.go	78.22% <0.00%> (ø)
tx/textual/valuerenderer/string.go	66.66% <0.00%> (ø)
tx/textual/valuerenderer/bytes.go	62.50% <0.00%> (ø)
tx/textual/valuerenderer/message.go	64.22% <0.00%> (ø)
tx/textual/valuerenderer/dec.go	50.00% <0.00%> (ø)
tx/textual/valuerenderer/coins.go	73.17% <0.00%> (ø)
tx/textual/valuerenderer/valuerenderer.go	72.41% <0.00%> (ø)
... and 1 more

[tac0turtle]

nice cleanup