When cloning a snippet, if it had some previews displayed, the previews
may be cloned with it. This is not a good behavior because the clone
is a new snippet so it should not have all the preview classes that were
added when editing. Moreover, these previews could also cause bugs.
To solve this, an idea could be to call the `cleanForSave` function of
all its options before cloning the snippet. But the problem is that in
some options, the `cleanForSave` function does more than simply clean
the UI (as it was originally supposed to) and so it cannot be used for
that purpose only.
As a solution, this commit adds a new function called `cleanUI` whose
exclusive purpose will be to clean the snippet UI. In the future, it
will replace the `cleanForSave` function.
task-3369695
Part-of: odoo/odoo#136683
Co-authored-by: qsm-odoo <qsm@odoo.com>
