Parse canonical function

[ilonatommy]

Parses e.g.:

(core func (;2;) (canon lower (func 0) (memory 0) string-encoding=utf8))
(func (;1;) (type 2) (canon lift (core func 3) (memory 0) (realloc 1) string-encoding=utf8))

cc @AaronRobinsonMSFT