Add write access request form

[timtebeek]

What's changed?

Added write access request form, which will then show up in each OpenRewrite repository, when people go to open a new issue.

What's your motivation?

We want to document the way people can get involved with the project, especially for authors of library and frameworks we already cover.

Anything in particular you'd like reviewers to focus on?

• Is it clear enough that we won't as easily grant write access to just anyone,
  but specifically to people already involved with the library or framework covered in each module?
• Is it sufficiently clear from the comment at the bottom that we do expect some form of commitment to the project?
• Any other fields we might like to ask about?

Have you considered any alternatives or workarounds?

We could also only have this form in a dedicated repository for access requests, but that makes it harder to find when you come in through for instance rewrite-hibernate.

Any additional context

openrewrite/rewrite-docs#188

[timtebeek]

A preview of the form is here: https://github.com/openrewrite/.github/blob/tim/write_access_request_form/.github/ISSUE_TEMPLATE/write_access_request.yml

[rpau]

LGTM

[mike-solomon]

Two minor suggestions but other than that looks good to me. Thanks for doing this!