[Clarity-4] `to-ascii?`

[obycode]

Conversion to string-ascii: to-ascii?

Originally proposed here.

to-ascii? is a new Clarity function that converts simple values into their
string-ascii representations.

• Input: int | uint | bool | principal | (buff 524284) |
  (string-utf8 1048571)
• Output: (response (string-ascii 1048571) uint)
• Signature: (to-ascii? value)
• Description: Returns the string-ascii representation of the input value
  in an ok response on success. The only error condition is if the input type
  is string-utf8 and the value contains non-ASCII characters, in which case,
  (err u1) is returned.
• Example:

  (to-ascii? true) ;; Returns (ok "true")
  (to-ascii? 42) ;; Returns (ok "42")
  (to-ascii? 'SP2QEZ06AGJ3RKJPBV14SY1V5BBFNAW33D96YPGZF) ;; Returns (ok "SP2QEZ06AGJ3RKJPBV14SY1V5BBFNAW33D96YPGZF")
  (to-ascii? 0x12345678) ;; Returns (ok "0x12345678")

See SIP proposal