Accept force option on commit via API

What does this MR do?

This MR adds a force option to Commits API when creating a commit. When set to true, the branch won't be validated if it already exists and will proceed to making a request to commit file/s to Gitaly.

gitaly-proto MR: gitaly-proto!263 (merged)

gitaly MR: gitaly!1077 (merged)

TODOs

• Update gitaly-proto gem when the version this MR requires gets released
• Update GITALY_SERVER_VERSION when the version this MR requires gets released

What are the relevant issue numbers?

#45035 (closed)

Does this MR meet the acceptance criteria?

• Changelog entry added, if necessary
• Documentation created/updated via this MR
• Documentation reviewed by technical writer or follow-up review issue created
• Tests added for this feature/bug
• Tested in all supported browsers
• Conforms to the code review guidelines
• Conforms to the merge request performance guidelines
• Conforms to the style guides
• Conforms to the database guides
• Link to e2e tests MR added if this MR has Requires e2e tests label. See the Test Planning Process.
• Security reports checked/validated by reviewer

Closes #45035 (closed)