Separate account getters from client/context

[alessio]

Closes: #4543

• Linked to github-issue with discussion and accepted design OR link to spec that describes this work.
• Wrote tests
• Updated relevant documentation (docs/)
• Added a relevant changelog entry: clog add [section] [stanza] [message]
• rereviewed Files changed in the github PR explorer

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For Admin Use:

• Added appropriate labels to PR (ex. wip, ready-for-review, docs)
• Reviewers Assigned
• Squashed all commits, uses message "Merge pull request #XYZ: [title]" (coding standards)

[codecov]

Codecov Report

Merging #4579 into master will increase coverage by 0.04%.
The diff coverage is 41.17%.

@@            Coverage Diff             @@
##           master    #4579      +/-   ##
==========================================
+ Coverage   52.61%   52.66%   +0.04%     
==========================================
  Files         263      264       +1     
  Lines       16464    16483      +19     
==========================================
+ Hits         8662     8680      +18     
  Misses       7154     7154              
- Partials      648      649       +1

[fedekunze]

looks good but I don't like the extra wrapper on the NodeQuerier interface

[sabau]

Can we add a make command and [or] some doc on how to manage/update/create mocks using mockgen, or just the example of how you achieved it here

[alexanderbez]

ACK

[sabau]

ACK

Fede and I talked through the changes. Hence dismissing the review.

[JimLarson]

Please disregard the previous unrelated PR - was supposed to be an issue in a different repo.