Enable use of non-user token

[langecode]

Clear and concise description of the problem

Currently builds are executed using a token associated with the used that activated the repository for building. When the token expires or the user is deactivated the build will start failing.

Suggested solution

A token not associated to a specific user should be used stored on the repo in the database.

Alternative

No response

Additional context

No response

Validations

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