The purpose of this commit is to improve the domain selector UX with
multiple little changes:
- The model field selector popover is now autofocused when opened
- Removal of a div that appeared during a hover on "add leaf" and
"ellipsis button"
- Caret icon next to the root node selector
- Minor CSS changes
task-2861497
closesodoo/odoo#99321
Signed-off-by: Géry Debongnie <ged@odoo.com>