feat(vcs-aggregated-checks): exposes VCS checks settings in the available VCS integrations

[silviutanasa]

Description of the change

New:
As part of the VCS Aggregated checks epic (https://app.clickup.com/t/8694knv2g), we added support, for the new "vcs_checks" option, to the existing VCS integrations from our terraform provider.
This change affects only the exiting supported VCS integrations terraform data and resources.
Feature demo: https://www.loom.com/share/4f1fad2530b846aa8d56d6b1d8151990

Improvements:
Because the "SPACELIFT_API_KEY_ENDPOINT" config key was using a Github secret, and because we don't consider it to be a sensitive value, for simplicity, we defined it in the infra repo and used it directly.

Caveats:
The VCS Aggregated checks is under a Feature flag, so exposing this option in the provider can cause issues to the clients that want to use it, but don't have the Feature flag enabled.

Type of change

• Bug fix (non-breaking change that fixes an issue)
• New feature (non-breaking change that adds functionality)
• Breaking change (fix or feature that would cause existing functionality to not work as expected)
• Documentation (non-breaking change that adds documentation)

Checklists

Development

• Lint rules pass locally
• The code changed/added as part of this pull request has been covered with tests
• All tests related to the changed code pass in development
• Examples for new resources and data sources have been added
• Default values have been documented in the description (e.g., "Dummy: (Boolean) Blah blah. Defaults to false.)
• If the action fails that checks the documentation: Run go generate to make sure the docs are up to date

Code review

• This pull request has a descriptive title and information useful to a reviewer. There may be a screenshot or screencast attached
• Pull Request is no longer marked as "draft"
• Reviewers have been assigned
• Changes have been reviewed by at least one other engineer

[mbialon]

LGTM