This commit updates the tour service so that triggers/actions can
be run in a shadow DOM.
In order to configure the tour to use the shadow DOM, the following
configurations options are added:
- `shadow_dom` on the tour configuration. This key must be
a valid selector matching the target shadow host element. All triggers/
actions of the tour will then be performed in its `ShadowRoot`.
- `shadow_dom` on any step of the tour. This value could either be
a valid selector matching the target shadow host element or false.
The behavior is the following:
- undefined: the step inherit the `shadowDOM` configuration from its
tour.
- string: the step triggers/actions will be performed in the
`ShadowRoot`related to the host matching the given selector.
- false: the step triggers/actions will be performed in the light
DOM.
part of task-2212347
Part-of: odoo/odoo#122834