This commit adds a new SelectMenu component. This component makes it
possible to search for options for a select element. It can be used to
replace the jquery select2 element for most cases.
Changes have been made to the Dropdown component as well as the position
hook, to allow the menu to be placed with the same width than the toggler,
using the 'fit' variant. Tests have been added to assert this position
feature.
Tests have been added to make sure the behavior of this component is
working as expected, and let the core element's usage being asserted.
Part-of: odoo/odoo#106265
Co-authored-by: luvi <luvi@odoo.com>
