MDL-84324 core: Fix Bootstrap dropdown key listeners

Bootstrap EventHandler is managing the keydown event at document
level in the capture phase. That is conflicting with dropdown elements
with form autocomplete inputs inside, because when suggestions panel is
open, pressing the "Esc" key will close the whole dropdown.
This commit fixes that behaviour by realocating the Bootsrap dropdown
event listener to the body instead of the document.

lib/amd/src/form-autocomplete.js

@@ -31,6 +31,7 @@ define([
     'core/aria',
     'core_form/changechecker',
     'core/popper2',
+    'theme_boost/bootstrap/dom/event-handler',
 ], function(
     $,
     log,
@@ -40,7 +41,8 @@ define([
     LoadingIcon,
     Aria,
     FormChangeChecker,
-    Popper
+    Popper,
+    EventHandler,
 ) {
     // Private functions and variables.
     /** @var {Object} KEYS - List of keycode constants. */
@@ -1083,6 +1085,16 @@ define([
                 });
             }
         }
+
+        // Add a Bootstrap keydown handler to close the suggestions list preventing the hole Dropdown close.
+        EventHandler.on(document, 'keydown.bs.dropdown.data-api', '.dropdown-menu', (event) => {
+            const pendingPromise = addPendingJSPromise('addNavigation-' + state.inputId + '-' + event.key);
+            if (event.key === "Escape" && inputElement.attr('aria-expanded') === "true") {
+                event.stopImmediatePropagation();
+                return pendingPromise.resolve(closeSuggestions(state));
+            }
+            return pendingPromise.resolve();
+        });
     };
 
     /**