chore(state-transition): improving applyDeposit error handling

[abi87]

stateProcessor.applyDeposit assumed that the only possible error when querying for a validator was that the validator did not exist, in which case it creates it.
This is brittle. This PR handles errors differently. A validator is created only if ErrNotFound is returned, otherwise applyDeposit returns the error to the client and does not go ahead creating a new validator.

[codecov]

Codecov Report

Attention: Patch coverage is 0% with 23 lines in your changes missing coverage. Please review.

Project coverage is 22.07%. Comparing base (3e88d11) to head (3bcc022).

Files with missing lines	Patch %	Lines
...ad/pkg/state-transition/state_processor_staking.go	0.00%	12 Missing ⚠️
...ate-transition/pkg/core/state_processor_staking.go	0.00%	11 Missing ⚠️

Additional details and impacted files

@@                        Coverage Diff                        @@
##           storage-cleanup-err-not-found    #2062      +/-   ##
=================================================================
- Coverage                          22.09%   22.07%   -0.02%     
=================================================================
  Files                                357      357              
  Lines                              16192    16205      +13     
  Branches                              12       12              
=================================================================
  Hits                                3578     3578              
- Misses                             12463    12476      +13     
  Partials                             151      151              

Files with missing lines	Coverage Δ
...ate-transition/pkg/core/state_processor_staking.go	0.00% <0.00%> (ø)
...ad/pkg/state-transition/state_processor_staking.go	0.00% <0.00%> (ø)

[itsdevbear]

introducing cosmos deps to state-transition is bad

[abi87]

I agree, but I believe we have to properly handle the errors from state, however unlikely they are. Will work on finding a different way for this

[abi87]

Rebasing this PR on top of a couple of others, I managed to ditch the direct cosmos sdk dependency and have state-transition depend on storage instead