Automate the new release process

[trask]

For non-patch releases:

• Create release branch if it doesn't exist already
• Add a new commit to the release branch updating the version (remove -SNAPSHOT) in these files:
  • version.gradle.kts
  • examples/distro/build.gradle
  • examples/extension/build.gradle
• Decide if we want to use versioned urls in the docs and if so, add a new commit to the release branch updating those
• On success push to the release branch
• On success bump version in main branch
• Merge versioned url bump from release branch to main branch

For patch releases:

• Automatic cherry-pick requested commits to the release branch
• Add a new commit to the release branch updating the version in these files:
  • version.gradle.kts
  • examples/distro/build.gradle
  • examples/extension/build.gradle
• On success push to the release branch

Will need to request a CLA exception for this automation:

If pushing automatically-generated, non-copyrightable code using a bot account is required, an explanation should be sent to the Governance Committee for review and forwarding to the EasyCLA team to exempt the bot's commits from the CLA requirement.

https://github.com/open-telemetry/community/blob/main/docs/using-github-extensions.md#writing-your-github-actions-pipelines

[trask]

Adding a related comment from @anuraaga #4756 (comment)

I guess I generally don't like reviewing the same code twice. If it were clear from a PR title whether it is a clean cherry pick or not and just 100% rubber-stamp than it could be better but otherwise still tend towards not review for clean cherry picks since it's like reviewing the exact same code twice

[trask]

Resolved-ish by #5143