refactor: rename CLI module

[Borda]

So far, I found it more common to place the CLI functions to a __main__ instead of package scripts...

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Comparison is base (b510582) 99.41% compared to head (8bda462) 98.46%.

Additional details and impacted files

@@            Coverage Diff             @@
##           master     #166      +/-   ##
==========================================
- Coverage   99.41%   98.46%   -0.96%     
==========================================
  Files           5        6       +1     
  Lines         513      521       +8     
  Branches       87       91       +4     
==========================================
+ Hits          510      513       +3     
- Misses          2        8       +6     
+ Partials        1        0       -1     

Files	Coverage Δ
cachier/__main__.py	0.00% <ø> (ø)

... and 1 file with indirect coverage changes

---

Continue to review full report in Codecov by Sentry.

Legend - Click here to learn more
Δ = absolute <relative> (impact), ø = not affected, ? = missing data
Powered by Codecov. Last update b510582...8bda462. Read the comment docs.