607 contrib docs

[sepiariver]

Changes

The CONTRIBUTING.md documentation seems to be outdated as many (all?) of the referenced composer scripts no longer exist. This PR updates the documentation and adds a script in composer to run all php version-specific tests.

Also, for the docker commands to run, docker/entrypoint.sh must be executable. The file's mode was changed to 755

The benefits including hopefully helping contributors get up to speed faster and not face as much of a barrier to entry, potentially leading to higher quality PRs.

Considerations:

• Due to the fact that I was working on this in parallel with Management::getHttpClient errors are opaque when acquiring token #603, this branch has more atomic commits. Suggesting a squash and merge if the PR is accepted.
• I'm not sure what to do about the integration tests. Punting to another ticket

References

#607

Resolves #607

Testing

composer tests pass. The new composer tests:phpversions executes all the php version-specific tests and they pass.

Contributor Checklist

• I have read the Auth0 general contribution guidelines
• I have read the Auth0 Code of Conduct

[evansims]

LGTM! Thanks very much for bringing this up to date!

[github-actions]

This pull request has been automatically locked since there has not been any recent activity after it was closed. Please open a new issue for related bugs.