[FIX] mail: edit follower subtype should close dropdown

Before this commit, when editing subtype of a follower
(click on pencil icon to edit), the subtype dialog was
displayed while keeping the follower list dropdown open.

This happens because `FollowerList` makes use of
`Dropdown` and `DropdownItem`, and by default they manage
closing of dropdown item when clicking away of when clicking
on the dropdown item. However, when there are specific clickable
elements on the `DropdownItem`, the clicks do not auto-close the
dropdown menu.

This commit fixes the issue by specifically close the dropdown menu
when clicking on edit button of a follower in follower list.

Task-3435443

closes odoo/odoo#129413

X-original-commit: a33f60356ba7c12bd854eb0efe5c653ff1559495
Signed-off-by: Sébastien Theys (seb) <seb@odoo.com>
Signed-off-by: Alexandre Kühn (aku) <aku@odoo.com>

addons/mail/static/src/core/web/follower_list.js

@@ -69,6 +69,7 @@ export class FollowerList extends Component {
             follower,
             onFollowerChanged: () => this.props.onFollowerChanged?.(),
         });
+        document.body.click(); // hack to close dropdown
     }
 
     /**

addons/mail/static/tests/web/follower_tests.js

@@ -121,6 +121,7 @@ QUnit.test("click on edit follower", async (assert) => {
     assert.containsOnce($, "button[title='Edit subscription']");
 
     await click("button[title='Edit subscription']");
+    assert.containsNone($, ".o-mail-Follower");
     assert.verifySteps(["fetch_subtypes"]);
     assert.containsOnce($, ".o-mail-FollowerSubtypeDialog");
 });