feat(config): Add allowed_scopes

[TjazVracko]

Hi,

This PR adds support for allowed_scopes. It functions the same way as allowed_types, except that the default list is empty, which means that all scopes are allowed.

I hope the changes follow the expectations of this repo.
I am unsure about the changes I made to CHANGELOG.md and toreference.md and the commit message itself.

Details

This feature can be used by adding allowed_scopes to the config file:

allowed_scopes = ["list", "of", "allowed", "scopes"]

When using a scope not in the list, the following error is printed:

Disallowed scope `wrong` used, please use one of ["list", "of", "allowed", "scopes"]

Notes

Issue #7 mentions a scope "blacklist" as well. I thought about adding a disallowed_scopes config as well, but It seems like added complexity at this point. If you have both allowed and disallowed lists, you probably need to check that only one of them is present in the config at the same time + maybe other things I have not thought of.

If a feature for disallowed_scopes is also needed, I might code it up in the future if I have the time. But I feel like allowed_scopes can stand on its own.

Resolves #7

[coveralls]

Pull Request Test Coverage Report for Build 11333675108

Warning: This coverage report may be inaccurate.

This pull request's base commit is no longer the HEAD commit of its target branch. This means it includes changes from outside the original pull request, including, potentially, unrelated coverage changes.

• For more information on this, see Tracking coverage changes with pull request builds.
• To avoid this issue with future PRs, see these Recommended CI Configurations.
• For a quick fix, rebase this PR at GitHub. Your next report should be accurate.

Details

• 0 of 23 (0.0%) changed or added relevant lines in 2 files are covered.
• 1 unchanged line in 1 file lost coverage.
• Overall coverage decreased (-0.3%) to 5.24%

---

Changes Missing Coverage	Covered Lines	Changed/Added Lines	%
crates/committed/src/config.rs	0	9	0.0%
crates/committed/src/checks.rs	0	14	0.0%

Files with Coverage Reduction	New Missed Lines	%
crates/committed/src/config.rs	1	0.0%

Totals
Change from base Build 11128006904:	-0.3%
Covered Lines:	24
Relevant Lines:	458

---

💛 - Coveralls

[epage]

Thanks!