Add bounds-of-thing-at-point property for 'number'

Add bounds-of-thing-at-point property for 'number'

* lisp/thingatpt.el (thing-at-point-decimal-regexp)
(thing-at-point-hexadecimal-regexp): Extract regexps from...
(number-at-point): ...here.  Use them in 'number-at-point'.
(number): Add 'bounds-of-thing-at-point' property as
`forward-word' does not always return the right boundary,
e.g., in latex-mode buffers.  (Bug#69239)