First part for#16

The code is adapted fromclojure-mode, but I usedtreesit-* API wherever it was appropriate and possible. The most difficult part is dealing with metadata, I left comments describing how it works.

The function is bound toC-c SPC inclojure-ts-mode-map, similar toclojure-mode.

I also disabledtab-indent-mode by default forclojure-ts-mode, similar toclojure-mode, otherwise it tries to use tabs for alignment and sometimes it looks ugly.

Before submitting a PR mark the checkboxes for the items you've done (if you
think a checkbox does not apply, then leave it unchecked):

• The commits are consistent with ourcontribution guidelines.
• You've added tests (if possible) to cover your change(s). Bugfix, indentation, and font-lock tests are extremely important!
• You've runM-x checkdoc and fixed any warnings in the code you've written.
• You've updated the changelog (if adding/changing user-visible functionality).
• You've updated the readme (if adding/changing user-visible functionality).

Thanks!