async version of currentTree

[kaunteya]

Hi I have this snippet in my code

extension TreeSitterClient {
    func currentTree() async throws -> Tree? {
        try await withCheckedThrowingContinuation { continuation in
            currentTree() { result in
                switch result {
                case .failure: continuation.resume(returning: nil)
                case .success(let tree):
                    continuation.resume(returning: tree)
                }
            }
        }
    }
}

Do you think it would make sense to have this function in the repo? I can open a PR

[mattmassicotte]

I think this makes a lot of sense! That PR would be very appreciated.