Custom code transformations

[njordhov]

Clariform could support custom code transformations, like in this example:

(define-internal (something-internal)
 (ok true)
)

;; which then gets expanded as:

(define-public (something-internal)
 (begin
   (try! (is-dao-or-extension contract-caller))
   (ok true)
)

Suggested here:
https://discord.com/channels/1076608263983997008/1089945712944488458/1105172252154150973