✨ Add path arg to filter commits

[thlmenezes]

Summary

TL;DR filter commits by path on changelog generation works, but untested.

As discussed in #158, after this comment. One of the tasks to enabling per monorepo package changelogs is to filter commits from a folder.

The dependency responsible for fetching raw commits enables the path option from git log as seen in the docs here

Help Needed

• how to test this behavior with jest?
  • I've searched earlier this week how does git stores and tracks the folder structure, but could not understand enough to write a test case to improve code coverage with the new getCommits path option

Missing features

• tests
• docs

Test Plan

• run

node packages/gitmoji-changelog-cli/src/index.js --path packages/gitmoji-changelog-cli

• The command is expected to fail with FunctionalError: No changes found. You may need to fetch or pull the last changes.
• Add a new comment to the selected testing folder (i.e packages/gitmoji-changelog-cli)
• Rerun changelog command with path argument
• The result will be something along the lines of

<a name="0.0.1"></a>
## 0.0.1 (2022-03-06)

### Miscellaneous

- 🚧 test commit [[2640d11](https://github.com/thlmenezes/gitmoji-changelog/commit/2640d110fa580f6591df4fa188772c1b99f1f3ad)]

For reference, without the path argument my changelog for this pr becomes

<a name="0.0.1"></a>
## 0.0.1 (2022-03-06)

### Added

- ✨ path option in generateChangelog [[66b0da7](https://github.com/thlmenezes/gitmoji-changelog/commit/66b0da7746e10ab04cecc6e510e9128570f6ef94)]
- ✨ path option to getCommits [[0b5eaef](https://github.com/thlmenezes/gitmoji-changelog/commit/0b5eaef34408d938a4d9c2c3f8134edf96f32d2c)]

### Miscellaneous

- 🚧 test commit [[2640d11](https://github.com/thlmenezes/gitmoji-changelog/commit/2640d110fa580f6591df4fa188772c1b99f1f3ad)]