Support all merge options (merge commit, squash, rebase) in auto-merge

[benjyabr]

Describe the feature

Currently, when merging a pull request (PR) in GitHub, we have three merge strategies:

1. Create a merge commit
2. Squash and merge
3. Rebase and merge

We would like the ability to configure auto-merge to support all of these options, allowing teams to choose the appropriate strategy for their workflow.

Why is this feature important?

Our Git flow requires squashing all commits in a branch into a single commit to ensure that the commit history in the main branch is organized by PRs. This helps maintain a clean and traceable commit history.

Additional context

No response