refactor: migrate CPU from heim to sysinfo for all platforms

[ClementTsang]

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:

Remove the heim CPU feature for all platforms and fully switch over to sysinfo.

Issue

If applicable, what issue does this address?

Part of #812.

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
• Linux

Checklist

If relevant, ensure the following have been met:

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

[codecov]

Codecov Report

Patch coverage has no change and project coverage change: +0.19 🎉

Comparison is base (e8ae1a2) 25.71% compared to head (d2129fc) 25.91%.

Additional details and impacted files

@@            Coverage Diff             @@
##           master    #1035      +/-   ##
==========================================
+ Coverage   25.71%   25.91%   +0.19%     
==========================================
  Files          83       80       -3     
  Lines       14880    14766     -114     
==========================================
  Hits         3827     3827              
+ Misses      11053    10939     -114     

Flag	Coverage Δ
macos-12	26.77% <0.00%> (+0.18%)	⬆️
ubuntu-latest	26.56% <0.00%> (+0.16%)	⬆️
windows-2019	26.48% <0.00%> (+0.16%)	⬆️

Flags with carried forward coverage won't be shown. Click here to find out more.

Impacted Files	Coverage Δ
src/app/data_harvester.rs	0.00% <0.00%> (ø)
src/app/data_harvester/cpu.rs	0.00% <ø> (ø)
src/app/data_harvester/cpu/sysinfo.rs	0.00% <0.00%> (ø)
src/app/data_harvester/processes/linux.rs	19.43% <0.00%> (-1.35%)	⬇️

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