bug#56714: 28.1.90; html-mode-map binds M-o

[Daniel Mendler]

In Emacs 28 the global M-o binding for the face menu was removed. The
html-mode-map still binds the key, such that it is not free to use by
the user. Is it possible to (re)move this binding? html-mode uses the
face menu functionality. If a full removal is not possible, the face
menu could be moved to another key.

In GNU Emacs 28.1.90 (build 1, x86_64-pc-linux-gnu, X toolkit, cairo
version 1.16.0, Xaw scroll bars)
 of 2022-06-30 built on projects
Repository revision: f5421104e9753a2d3ead19ba31ac5ed1f3a5c03a
Repository branch: emacs-28
Windowing system distributor 'The X.Org Foundation', version 11.0.12004000
System Description: Debian GNU/Linux 10 (buster)