Updated flat_profile()

[nkasica]

• added and modified existing flat_profile() functionality

• resolves ENH: flat_profile have a sort option #139

• makes Tests: test flat profile #106 unnecessary

Future TODOs:

• resolve warnings in _match_caller_callee_by_level (unrelated to changes I made)

[codecov]

Codecov Report

❌ Patch coverage is 88.13559% with 7 lines in your changes missing coverage. Please review.
✅ Project coverage is 70.06%. Comparing base (afb4b69) to head (1150264).

Files with missing lines	Patch %	Lines
pipit/trace.py	81.08%	7 Missing ⚠️

Additional details and impacted files

@@             Coverage Diff             @@
##           develop     #152      +/-   ##
===========================================
+ Coverage    69.15%   70.06%   +0.91%     
===========================================
  Files           14       14              
  Lines         1744     1794      +50     
===========================================
+ Hits          1206     1257      +51     
+ Misses         538      537       -1     

Flag	Coverage Δ
unittests	70.06% <88.13%> (+0.91%)	⬆️

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

☔ View full report in Codecov by Sentry.
📢 Have feedback on the report? Share it here.

🚀 New features to boost your workflow:

• ❄️ Test Analytics: Detect flaky tests, report on failures, and find test suite problems.