$.isNumeric() returns FALSE for numeric strings

Problem/Motivation

js/jquery.deprecated.functions.js implements the helper as:

$.isNumeric = (obj) => {
  return !Number.isNaN(parseFloat(obj)) && Number.isFinite(obj);
};

Number.isFinite() does not coerce its argument, so it is false for every
string. The polyfill therefore disagrees with the jQuery implementation it
replaces:

Numeric strings are the main reason callers reach for $.isNumeric() at all:
values read from attributes, and form elements are strings.
Code that guards a value with it silently takes the other branch — a wrong
number rather than an error, which is harder to notice than a missing function.

Found while preparing a Drupal 11 upgrade: jquery-bar-rating guards its
stored rating with $.isNumeric(), and the module is exactly what is supposed
to keep that library working on jQuery 4.

The other helpers in the file are fine — isArray, isFunction, isWindow,
type, trim, camelCase and nodeName were compared against native
jQuery 3.7.1 across 18 inputs and match.

Proposed resolution

Use the definition from jQuery itself: accept numbers and strings, and check
that the value survives numeric coercion.

$.isNumeric = (obj) => {
  const type = $.type(obj);
  return (
    (type === 'number' || type === 'string') &&
    !Number.isNaN(obj - parseFloat(obj))
  );
};

Remaining tasks

- Review the patch.

The patch also fills in part of the existing @todo in
JqueryDeprecatedFunctionsJsTest::testDeprecatedJqueryFunctionsExistAtRuntime()
with eleven $.isNumeric() assertions covering numeric strings, plain numbers
and the falsy cases. They fail on 1.0.4 and pass with the fix.

User interface changes

None.

API changes

None — the helper starts behaving the way the jQuery API it restores is
documented to behave.

Data model changes

None