Function squash_commits

pub fn squash_commits<'repo>(
    repo: &'repo mut MutableRepo,
    sources: &[CommitWithSelection],
    destination: &Commit,
    keep_emptied: bool,
) -> BackendResult<Option<SquashedCommit<'repo>>>

Squash sources into destination and return a SquashedCommit for the resulting commit. Caller is responsible for setting the description and finishing the commit.