feature: option to have process tree entries be collapsed by default

[Bucket-Bucket-Bucket]

Description

A description of the change, what it does, and why it was made. If relevant (such as any change that modifies the UI), please provide screenshots of the changes:

Adds a command line option and config file option to have the process tree view have all entries collapsed by default.

Issue

If applicable, what issue does this address?

Closes: #1612

Testing

If relevant, please state how this was tested. All changes must be tested to work:

If this is a code change, please also indicate which platforms were tested:

• [ ] Windows
• [ ] macOS
• [x] Linux

Checklist

If relevant, ensure the following have been met:

• [x] Areas your change affects have been linted using rustfmt (cargo fmt)
• [x] The change has been tested and doesn't appear to cause any unintended breakage
• [x] Documentation has been added/updated if needed (README.md, help menu, doc pages, etc.)
• [ ] The pull request passes the provided CI pipeline
• [x] There are no merge conflicts
• [ ] If relevant, new tests were added (don't worry too much about coverage)

[codecov[bot]]

Codecov Report

Attention: Patch coverage is 12.00000% with 22 lines in your changes missing coverage. Please review.

Project coverage is 41.95%. Comparing base (196d6d1) to head (ca0abc8).

Files with missing lines	Patch %	Lines
src/widgets/process_table.rs	0.00%	20 Missing :warning:
src/app.rs	0.00%	1 Missing :warning:
src/options/args.rs	0.00%	1 Missing :warning:

Additional details and impacted files

@@             Coverage Diff             @@
##             main    #1627       +/-   ##
===========================================
- Coverage   54.73%   41.95%   -12.78%     
===========================================
  Files         114      114               
  Lines       17685    17699       +14     
===========================================
- Hits         9680     7426     -2254     
- Misses       8005    10273     +2268     

Flag	Coverage Δ
macos-12	37.40% <12.00%> (-0.02%)	:arrow_down:
ubuntu-latest	43.73% <12.00%> (-13.45%)	:arrow_down:
windows-2019	37.31% <12.00%> (-0.02%)	:arrow_down:

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[ClementTsang]

My bad, forgot to review this - I'll rebase and review in a bit.

[ClementTsang]

Apparently I can't push to this branch (despite github saying I can...?), will close this in favour of another PR that has a few changes. Will still credit, dw.