chore: (x/authz) add helpers AppendBytes, ParseByteSlice

[atheeshp]

Description

Closes: #11578

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Author Checklist

All items are required. Please add a note to the item if the item is not applicable and
please add links to any relevant follow up issues.

I have...

• included the correct type prefix in the PR title
• added ! to the type prefix if API or client breaking change
• targeted the correct branch (see PR Targeting)
• provided a link to the relevant issue or specification
• followed the guidelines for building modules
• included the necessary unit and integration tests
• added a changelog entry to CHANGELOG.md
• included comments for documenting Go code
• updated the relevant documentation or specification
• reviewed "Files changed" and left comments if necessary
• confirmed all CI checks have passed

Reviewers Checklist

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your handle next to the items reviewed if you only reviewed selected items.

I have...

• confirmed the correct type prefix in the PR title
• confirmed ! in the type prefix if API or client breaking change
• confirmed all author checklist items have been addressed
• reviewed state machine logic
• reviewed API design and naming
• reviewed documentation is accurate
• reviewed tests and test coverage
• manually tested (if applicable)

[codecov]

Codecov Report

Merging #11713 (8e7751f) into master (79031f2) will increase coverage by 0.02%.
The diff coverage is 100.00%.

@@            Coverage Diff             @@
##           master   #11713      +/-   ##
==========================================
+ Coverage   65.91%   65.94%   +0.02%     
==========================================
  Files         667      667              
  Lines       70460    70466       +6     
==========================================
+ Hits        46441    46466      +25     
+ Misses      21324    21304      -20     
- Partials     2695     2696       +1     

Impacted Files	Coverage Δ
types/utils.go	76.05% <100.00%> (+9.38%)	⬆️
x/authz/keeper/keys.go	93.61% <100.00%> (-1.47%)	⬇️
crypto/keys/internal/ecdsa/privkey.go	84.21% <0.00%> (+1.75%)	⬆️
x/distribution/simulation/operations.go	90.27% <0.00%> (+9.72%)	⬆️

[alexanderbez]

LGTM