Murisi/set masp params migration

[murisi]

Describe your changes

Implemented a hard-fork migration that allows shielded reward parameters to be set. This is useful when testing shielded rewards on mainnet clones.

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:

[grarco]

Minor comments but looks good to me

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 0.00%. Comparing base (c2cddf3) to head (a68fc5d).
Report is 20 commits behind head on main.

Additional details and impacted files

@@     Coverage Diff      @@
##   main   #4589   +/-   ##
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