fix(ui5-date-picker): select date with SPACE on keyup (#2279)

This PR complements the following PR #2276
to fix everything requested by the referenced issue, more specifically forcing date selection with SPACE to take place on keyup, instead of keydown as at the moment.

FIXES: #2268

Author: ilhan007

packages/main/src/DayPicker.hbs

@@ -2,6 +2,7 @@
 	class="ui5-dp-root"
 	style="{{styles.wrapper}}"
 	@keydown={{_onkeydown}}
+	@keyup={{_onkeyup}}
 	@mousedown={{_onmousedown}}
 	@mouseup={{_onmouseup}}
 >

packages/main/src/DayPicker.js

@@ -453,7 +453,8 @@ class DayPicker extends UI5Element {
 		}
 
 		if (isSpace(event)) {
-			return this._handleSpace(event);
+			event.preventDefault();
+			return;
 		}
 
 		if (isHomeCtrl(event)) {
@@ -481,6 +482,12 @@ class DayPicker extends UI5Element {
 		}
 	}
 
+	_onkeyup(event) {
+		if (isSpace(event)) {
+			this._handleSpace(event);
+		}
+	}
+
 	_handleEnter(event) {
 		event.preventDefault();
 		if (event.target.className.indexOf("ui5-dp-item") > -1) {