[FIX] web_editor: fix inputs usable with the arrows and without preview

The user can use arrows up/down to change the value of an input in the
editor (inputs that handle numerical values). Unfortunately if this
input does not trigger a preview (data-no-preview="true"), the
modifications made by the user with arrow up/down are not saved. This
commit solves this problem by notifying that the value has changed at
the input blur (or on ENTER key press) if arrow up/down has been used.

Details:
Since we use text inputs in the editor, (even to manage numerical value)
the management of arrow up/down is done manually, so Javascript does not
consider the value of the input has changed and therefore does not
trigger the change event. Another solution would have been to say that
when we know that the input is going to manage a numeric value, we put
the type="number" on it but in this case, the change event is triggered
at each arrow up/down which breaks the fact that some inputs do not want
to have a preview.

Steps to reproduce the problem:
- Drop the Products block in a page
- Use arrow up/down to change the value of the Slider Speed input
- Save and Edit again
=> The change made with arrow up/down has not been saved.

task-2765868

closes odoo/odoo#88791

Signed-off-by: Arthur Detroux (ard) <ard@odoo.com>