Add support for "bright" ANSI colors in term-mode

Add support for "bright" ANSI colors in term-mode

* list/term.el (ansi-term-color-vector): Add new faces.
(term-color-white): Tweak colors.
(term-color-bright-black, term-color-bright-red, term-color-bright-green)
(term-color-bright-yellow, term-color-bright-blue)
(term-color-bright-magenta, term-color-bright-cyan)
(term-color-bright-white): New faces.
(term--maybe-brighten-color): New function.
(term-handle-colors-array): Handle bright colors.
* test/lisp/term-tests.el (term-colors, term-colors-bold-is-bright):
New functions.