Add parse and dispatch strategy

[SeanBryan51]

The current method of executing subcommands can be improved using a "parse and dispatch" strategy. Whereby you don't need to run a conditional to work out which subcommand to use.

This change refactors the Benchcab class so that its "public" methods can be dispatched easily when inspecting the argparse.Namespace object returned by the command line parser.

Fixes #196

[codecov[bot]]

Codecov Report

Merging #198 (474d183) into main (d1192c9) will decrease coverage by 1.55%. Report is 1 commits behind head on main. The diff coverage is 45.79%.

@@            Coverage Diff             @@
##             main     #198      +/-   ##
==========================================
- Coverage   86.74%   85.19%   -1.55%     
==========================================
  Files          27       27              
  Lines        1396     1385      -11     
==========================================
- Hits         1211     1180      -31     
- Misses        185      205      +20     

Files	Coverage Δ
benchcab/cli.py	100.00% <100.00%> (ø)
tests/test_cli.py	100.00% <100.00%> (ø)
benchcab/main.py	50.00% <50.00%> (ø)
benchcab/benchcab.py	23.12% <23.88%> (-9.84%)	:arrow_down:

[SeanBryan51]

Integration tests seem to be working. Merging now.