Post-337 patches: docs, fixes, minor refactoring

[TTsangSC]

Miscellaneous stuff that was discussed during #337 but didn't make the cut before the merge.

• docs/**/*.rst:
  Removed the :private-members: directive so that we don't give mixed signals as to what is in the public(-ly documented) API
• kernprof.py
  • main(), _write_preimports():
    Minor formatting fixes for stdout/logging output
  • _dump_filtered_stats():
    Fixed error (by early-exiting) because kernprof.ContextualProfile is incompatible with (and doesn't need) the filtering of profiling results
  • _main_profile():
    Unnested redundant try block, and stopped suppressing BaseExceptions (since the profiling output is written anyway)
• line_profiler/profiler_mixin.py::ByCountProfilerMixin
  • _get_underlying_functions():
    • Refactored section handling classes and properties into separate methods to reduce complexity
    • Refactored away use of functools.partial where possible
    • Added clarifying comments
  • wrap_class():
    Refactored away use of functools.partial where possible
• tests/test_kernprof.py::test_kernprof_verbosity():
  Scrubbed remnant of tests for code output (removed in 447ab0a to 1b88d97)

[codecov]

Codecov Report

Attention: Patch coverage is 41.93548% with 18 lines in your changes missing coverage. Please review.

Project coverage is 69.14%. Comparing base (0b8cc7e) to head (733495c).
Report is 7 commits behind head on main.

Files with missing lines	Patch %	Lines
line_profiler/profiler_mixin.py	41.93%	18 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main     #353      +/-   ##
==========================================
- Coverage   69.45%   69.14%   -0.32%     
==========================================
  Files          18       18              
  Lines        1611     1614       +3     
  Branches      341      344       +3     
==========================================
- Hits         1119     1116       -3     
- Misses        415      420       +5     
- Partials       77       78       +1     

Files with missing lines	Coverage Δ
line_profiler/profiler_mixin.py	41.92% <41.93%> (+1.45%)	⬆️

... and 2 files with indirect coverage changes

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