bug#42384: octal escape sequences old fashioned

[積丹尼 Dan Jacobson]

(info "(emacs) Text Display") says:

      The raw bytes with codes ‘U+0080’ (octal 200) through ‘U+009F’ (octal
   237) are displayed as “octal escape sequences”, with the ‘escape-glyph’
   face.  For instance, character code ‘U+0098’ (octal 230) is displayed as
   ‘\230’.  If you change the buffer-local variable ‘ctl-arrow’ to ‘nil’,
   the ASCII control characters are also displayed as octal escape
   sequences instead of caret escape sequences.

OK but octal is rather old fashioned so the user should be given the
choice of hex, etc.

emacs-version "26.3"