[FIX] web_editor: fix anchor click on submit button

Context:
1) Edit mode
2) Click on anchor edition button of website form submit button
3) Traceback occurs

The "focus" triggered on $editable element in editor's 'getLinkInfo()'
discards user's text selection on submit button, as a result,
'range.create()' method returns null since no selection is found.

Note: the bug only occurred in Chrome.

Note 2: [1] apparently tried to solve the same issue but the fix was not
        solving it correctly, at least not in all cases.

[1]: https://github.com/odoo/odoo/commit/da14e4449e5e318eb72e1b9f268fb797adb0c6a6



opw-2443441

closes odoo/odoo#65875

Signed-off-by: Quentin Smetz (qsm) <qsm@odoo.com>