Original PR description

Before this commit, the colorpalette for the background color would
not display custom colors already on the page. The issue appeared in
17.0 and worked in 16.0 before the conversion of wysiwyg to owl.
github.com/https://github.com/odoo/odoo/pull/118966

The "getEditableCustomColors" method was not forwarded and therefore
we used the default function, returning nothing.

Steps to reproduce the issue:
- Add a snippet
- Set the background / font color of the snippet to a custom color
- Add another snippet
- Open the colorpicker for the text color
(The colorpicker have access to the custom color set above)
- Open the colorpicker for the background color
(The colorpicker does not have access to the custom color set above)

task-3806989

Original PR description

Steps to Reproduce:
1. Create an anchor link for any dropped snippet.
2. Insert the link through the link popover.
3. Enable the "Open in New Window" option.
4. Click on Save.
5. Click on the link.

Issue:
Even though the "Open in New Window" option is enabled, the page scrolls in the same tab instead of opening in a new window and scrolling to the targeted view.

Reason:
When an anchor link has target="_blank", `ev.preventDefault()` was still being called, which prevented the browser from performing its default behavior of opening the link in a new tab.

Fix:
Removed `ev.preventDefault()` for such links, as the expected behavior is to open them in a new tab whenever target="_blank" is set. Additionally, the offcanvas mobile-specific logic has been removed, as it is no longer necessary now that `ev.preventDefault()` is no longer used.

task-5104027