Optimize ansi-color.el

Optimize ansi-color.el

(ansi-color-context-region):
(ansi-color-context): Adjust doc string to the new format of
ansi-color context.

(ansi-color--find-face): Rename to ansi-color--face-vec-face
(ansi-color--face-vec-face): Adjust to the new format ansi-color
context.

(ansi-color-filter-apply):
(ansi-color-apply):
(ansi-color-filter-region):
(ansi-color-apply-on-region): Adjust to the new format of ansi-color
context in order to speed these functions up.

(ansi-color-apply-sequence): Make it obsolete.
(ansi-color--update-face-vec): New function to handle the new format
of ansi-color context.

(ansi-color-get-face-1): Make obsolete as this function isn't used any
more (bug#50806).