Add offline and fee-payer utilities to CLI vote module (backport #21579)

[mergify]

This is an automatic backport of pull request #21579 done by Mergify.
Cherry-pick of 873fe81 has failed:

On branch mergify/bp/v1.8/pr-21579
Your branch is up to date with 'origin/v1.8'.

You are currently cherry-picking commit 873fe81bc.
  (fix conflicts and run "git cherry-pick --continue")
  (use "git cherry-pick --skip" to skip this patch)
  (use "git cherry-pick --abort" to cancel the cherry-pick operation)

Changes to be committed:
	modified:   cli/tests/stake.rs
	modified:   docs/src/offline-signing.md

Unmerged paths:
  (use "git add <file>..." to mark resolution)
	both modified:   cli/src/cli.rs
	both modified:   cli/src/vote.rs
	both modified:   cli/tests/vote.rs

To fix up this pull request, you can check it out locally. See documentation: https://docs.github.com/en/github/collaborating-with-pull-requests/reviewing-changes-in-pull-requests/checking-out-pull-requests-locally

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[mergify]

automerge label removed due to a CI failure

[codecov]

Codecov Report

Merging #21648 (df81cd7) into v1.8 (4d3352e) will decrease coverage by 0.1%.
The diff coverage is 77.1%.

@@            Coverage Diff            @@
##             v1.8   #21648     +/-   ##
=========================================
- Coverage    81.7%    81.6%   -0.2%     
=========================================
  Files         456      459      +3     
  Lines      129990   130369    +379     
=========================================
+ Hits       106240   106413    +173     
- Misses      23750    23956    +206