Add commit url output option

[clamey]

Adds an optional boolean flag called --commit-urls or --no-commit-urls for outputting commit URLs for easier commit validation, which defaults to off to keep backwards compatibility.

Without the new flag, it's the same output as before this change:

topher> pipenv run python3 github-repo-committers.py --access_token $ACCESS_TOKEN --repo_name "kaakaww/contributors_tool"                                                                         <region:us-west-2>
In the repository 'kaakaww/contributors_tool', there are 4 contributor(s) over 90 days with the earliest commit on 2021-08-04 01:05:47.
Here is the list of Github contributors:
sgerlach: 2021-11-02T01:05:47Z
jeremygoldsmith: 2021-10-31T04:07:22Z
azconger: 2023-03-22T23:23:11Z
clamey: 2024-09-09T17:31:05Z

With the new flag, we get a URL for each commit:

topher> pipenv run python3 github-repo-committers.py --access_token $ACCESS_TOKEN --repo_name "kaakaww/contributors_tool" --commit_urls                                                             <region:us-west-2>
In the repository 'kaakaww/contributors_tool', there are 4 contributor(s) over 90 days with the earliest commit on 2021-08-04 01:05:47.
Here is the list of Github contributors:
sgerlach: 2021-11-02T01:05:47Z, https://github.com/kaakaww/contributors_tool/commit/66eee5bb5b32d93562ccf6891a24bf747c621a10
jeremygoldsmith: 2021-10-31T04:07:22Z, https://github.com/kaakaww/contributors_tool/commit/48fa39f9b056cff16c7e3cb39bf598ce3914fc79
azconger: 2023-03-22T23:23:11Z, https://github.com/kaakaww/contributors_tool/commit/c9e8b1a7c52705075d35654a863ae96418f11ea0
clamey: 2024-09-09T17:31:05Z, https://github.com/kaakaww/contributors_tool/commit/cb667e6422ea0acea2dcfa15c4550adf85856793