validate validator metadata

[tzemanovic]

Describe your changes

fixes #4033

Checklist before merging

• If this PR has some consensus breaking changes, I added the corresponding breaking:: labels
  • This will require 2 reviewers to approve the changes
• If this PR requires changes to the docs or specs, a corresponding PR is opened in the namada-docs repo
  • Relevant PR if applies:
• If this PR affects services such as namada-indexer or namada-masp-indexer, a corresponding PR is opened in that repo
  • Relevant PR if applies:

[codecov]

Codecov Report

Attention: Patch coverage is 76.92308% with 18 lines in your changes missing coverage. Please review.

Project coverage is 74.56%. Comparing base (63eaf11) to head (1ab9f63).
Report is 19 commits behind head on main.

Files with missing lines	Patch %	Lines
crates/proof_of_stake/src/types/mod.rs	68.57%	11 Missing ⚠️
crates/proof_of_stake/src/vp.rs	76.92%	3 Missing ⚠️
crates/apps_lib/src/config/genesis/transactions.rs	50.00%	2 Missing ⚠️
crates/proof_of_stake/src/error.rs	0.00%	1 Missing ⚠️
crates/proof_of_stake/src/storage.rs	95.83%	1 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #4036      +/-   ##
==========================================
+ Coverage   74.31%   74.56%   +0.25%     
==========================================
  Files         341      341              
  Lines      107401   107413      +12     
==========================================
+ Hits        79815    80097     +282     
+ Misses      27586    27316     -270     

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[brentstone]

LGTM, thx so much!