Remove era type parameter from MemoBytes

[teodanciu]

Description

MemoBytes type no long needs the era parameter, following the removal of crypto parameterization.
This PR is removing this type parameter from MemoBytes and making the necessary adjustments at the usage site.

Closes #4842

Checklist

• Commits in meaningful sequence and with useful messages
• Tests added or updated when needed
• CHANGELOG.md files updated for packages with externally visible changes
  
  New section is never added with the code changes. (See RELEASING.md)
• Versions updated in .cabal and CHANGELOG.md files when necessary, according to the
  versioning process.
• Version bounds in .cabal files updated when necessary
  
  If you change the bounds in a cabal file, that package itself must have a version increase. (See RELEASING.md)
• Code formatted (use scripts/fourmolize.sh)
• Cabal files formatted (use scripts/cabal-format.sh)
• hie.yaml updated (use scripts/gen-hie.sh)
• Self-reviewed the diff

[lehins]

It makes me happy that we can finally make MemoBytes applicable to non-era parametric types!
There is a bit of simplification and few minor fixups that can be done in the PR, but other that that it looks great!

[lehins]

Beautiful! Thank you!