Improve performance of clojure-ts-align

[rrudakov]

Cache semantic indentation rules for a single clojure-ts-align run to avoid lookup for every repeating symbol.

Context: I noticed that clojure-ts-align can be quite slow when aligning very large expressions (i.e. large EDN system configurations or large integration test functions). clojure-ts-mode performs lookup for an indentation rule for every symbol, with CIDER connected it also involves nREPL communication.

I've been using this improved version for a very long time and haven't noticed any downsides.

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Thanks!

[bbatsov]

Sorry for sitting on this so long, it slipped past me when you opened it.

I stubbed clojure-ts-get-indent-function with a 1ms delay to stand in for an nREPL round-trip and aligned a 200-clause cond: 406 lookups down to 3, 0.64s down to 0.13s. Good win.

Heads up that main moved under you and this conflicts now. Comments inline, nothing blocking.