Improve performance of semantic indentation by caching rules

[rrudakov]

I've noticed that reindenting big file is pretty slow, profiler report indicated that the bottleneck is the calculation of combined indentation rules from default settings and user customizations:

(seq-union (or rules clojure-ts-semantic-indent-rules)
             clojure-ts--semantic-indent-rules-defaults
             (lambda (e1 e2) (equal (car e1) (car e2))))

this is called every time we need to calculate indentation for a single line.

This PR introduces buffer local variable clojure-ts--semantic-indent-rules-cache which stores pre-calculated rules. This variable is set when clojure-ts-mode is activated and updated every time when clojure-ts-semantic-indent-rules is updated or file local variables are updated (in case when indentation rules are defined in .dir-locals.el for example.

---

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 our contribution guidelines.

• You've run M-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!