bug#56239: 28.1; Cannot send signals by name to inferior process by calling signal-process interactively

["Daniel Martín via Bug reports for GNU Emacs, the Swiss army knife of text editors" <bug-gnu-emacs@gnu.org>]

The scenario is a user that wants to send the signal SIGUSR1 (for
example) to an inferior process and does the following:

Switch to the buffer associated with the inferior process.

M-x signal-process RET

Press RET for the process (so that the process associated with the
current buffer is used).

For the signal code, type 'SIGUSR1 (or "SIGUSR1", or SIGUSR1).

The operation fails with the message "Please enter a number".

The docstring of signal-process says that sending a signal by name
should be possible:

"SIGCODE may be an integer, or a symbol whose name is a signal name."

If we call the command non-interactively, it works correctly:

M-: (signal-process nil 'SIGUSR1)

In GNU Emacs 28.1 (build 1, aarch64-apple-darwin21.1.0, NS appkit-2113.00 Version 12.0.1 (Build 21A559))
 of 2022-04-04 built on armbob.lan
Windowing system distributor 'Apple', version 10.3.2113
System Description:  macOS 12.4

Configured using:
 'configure --with-ns '--enable-locallisppath=/Library/Application
 Support/Emacs/${version}/site-lisp:/Library/Application
 Support/Emacs/site-lisp' --with-modules'

Configured features:
ACL GMP GNUTLS JSON LIBXML2 MODULES NOTIFY KQUEUE NS PDUMPER THREADS
TOOLKIT_SCROLL_BARS ZLIB

Important settings:
  value of $LANG: en_ES.UTF-8
  locale-coding-system: utf-8-unix