binascii: drive the nine keyword-accepting functions off the marker ABI

Register b2a_hex/hexlify, a2b_qp/b2a_qp, and a2b_base64/b2a_base64/b2a_uu
through the inline_functions: arm so #[pyre_function] derives their
Signature and the caller binds keywords into positional slots. Register
the all-positional-only crc32/crc_hqx through a hand-built
SignatureBuilder (marker_posonly after every append) in extra_init:,
since #[posonly] on a parameter cannot mark a run with no trailing
parameter. Both take HOPELESS arity so the positional path routes
through the binder rather than the fixed-arity fast entry.

The bodies read PY_NULL-padded positional slots instead of peeling
split_builtin_kwargs / bind_builtin_kwargs; the two helpers and the
marker producer stay for the remaining null-sig callers.

crc32/crc_hqx report keyword and arity errors under the bare function
name (crc32() ...) the way funcrun_obj names an interp2app function,
dropping the manual binascii. prefix.

a2b_base64's strict_mode stays keyword-only, unchanged; interp_base64.py
marks no __kwonly__ there, so upstream keeps it positional-or-keyword.

Assisted-by: Claude

Author: youknowone