Avoid traceback when the click that triggered the rainbow man
is the click that closes it.

Example: The last step of a tour.

closes odoo/odoo#29969

Resulting in sphinx warnings or ill-formatted doc all the way to the
doc not building at all.

This rev. makes the Rainbowman stop listening to event
'clear_uncommitted_changes' on core.bus, as this event is about to
be removed (in a next commit). It was using it to destroy itself
when such an event was triggered (basically, when the current view
was left).

Instead, we removed the option 'click_close' as, when set to true,
which was the default, the rainbowman was destroyed as soon as the
user clicked outside the raibowman.

This commit introduces the 'rainbowification' feature to the web client
(and to some affected addons).  This feature is essentially a way to
display a nice friendly message when some business event happens.  For
example, a encouraging message is displayed when the user clear her/his
inbox, or when a salesman closes a deal.

The mechanism currently only displays a 'rainbowman', but could be
extended later to add other kind of animation.

There are a few different ways to display a 'rainbowman':
- any JS code can simply trigger_up an event ('show_effect') with some
  options: for example
    this.trigger_up('show_effect', {
        type: 'rainbow_man',
        fadeout: 'no',
        message: $done,
        click_close: false,
    });
- an action returned by the server can have an 'effect' key, with some
  options
- the do_execute_action method accepts a 'effect' option.  This is
  useful when one wants to specify a rainbow on an action button in a
  form view

Joint work with: dbh <dbh@odoo.com>, ged <ged@odoo.com>