This commit adds some discuss-related options in the command
palette.
- hotkeys to add channel (C) & chat (D), and start a meeting (M);
- namespaces `@` or `#` show mentionned and recent conversations
in Discuss app when search is empty;
Items show optional badge with needaction counter.
Mentions/Recent categories are only visible when there are no
search term. Indeed, `@term` searches for users while `#channel`
searches for channels, so these categories are meant to quickly
jump to recent and important conversations. When typing some
search terms, the fuzzy search has precedence over mentions/recent
criteria.
task-3330218
closesodoo/odoo#128896
Signed-off-by: Alexandre Kühn (aku) <aku@odoo.com>