Default for approval requirement for PRs

[confusedsushi]

Clear and concise description of the problem

Since version 3.0 or #4456 new repositories require approval by default. This breaks some workflows for me. My instance is running in a closed environment this restrictive setting is not needed and is currently just requiring some extra configuration for every single repository.

Suggested solution

Introduce an environment variable for the server (maybe DEFAULT_APPROVAL_REQUIREMENT) in which you define the default setting for new repositories. (Possible values none, prs_from_forked_repos, all_prs, all_events.)

Alternative

No response

Additional context

No response

Validations

• Checked that the feature isn't part of the next version already [https://woodpecker-ci.org/versions]
• Read the docs.
• Check that there isn't already an issue that request the same feature to avoid creating a duplicate.