refactor: cosmovisor name normalization & comparison

[alexanderbez]

Description

• Normalize (lower-case) upgrade name when parsing the plan file
• Perform case-insensitive name comparison in CheckUpdate
• Minor linting/style cleanup

---

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

All items are required. Please add a note if the item is not applicable and please add
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 #11608 (b9c1dc2) into master (5cbdad3) will decrease coverage by 0.15%.
The diff coverage is 54.51%.

@@            Coverage Diff             @@
##           master   #11608      +/-   ##
==========================================
- Coverage   66.05%   65.90%   -0.16%     
==========================================
  Files         712      677      -35     
  Lines       74400    71072    -3328     
==========================================
- Hits        49146    46837    -2309     
+ Misses      22228    21513     -715     
+ Partials     3026     2722     -304     

Impacted Files	Coverage Δ
baseapp/grpcserver.go	1.72% <0.00%> (-0.04%)	⬇️
client/flags/flags.go	20.00% <0.00%> (-0.69%)	⬇️
client/keys/show.go	75.34% <0.00%> (-3.54%)	⬇️
client/tx/tx.go	32.73% <0.00%> (ø)
cosmovisor/upgrade.go	75.72% <ø> (ø)
simapp/export.go	11.76% <0.00%> (-0.55%)	⬇️
snapshots/store.go	71.66% <0.00%> (ø)
types/module/module.go	70.58% <0.00%> (ø)
x/auth/client/cli/tx_sign.go	0.00% <0.00%> (ø)
x/staking/simulation/operations.go	74.36% <0.00%> (-0.52%)	⬇️
... and 82 more