EaElements ComboBox bugs

[seventil]

1.TableViewCombobox declares property int horizontalAlignment: Text.AlignHCenter, but the contentItem in ComboBox.qml does not bind horizontalAlignment. Users can't easily align the label text.
2. ComboBox.qml sets property int elide: Text.ElideMiddle, but also property int textFormat: Text.RichText. Qt disables text eliding when textFormat is RichText.
3. The indicator is positioned with x: control.width - width - control.rightPadding, but rightPadding includes indicator.width + spacing. The arrow is inset an extra indicator-wirth from the right edge, while contentItem's rightPadding doesn't have enough space - text and arrow overlap.
4. alias in ComboBox.qml:24 is broken: property var contentItemLabel: contentItemLabel collides with the contentItem's id: contentItemLabel in ComboBox.qml:94.

Proposed solutions:

1. Tie horizontalAlignment to the contentItem label inside ComboBox.qml.
2. Remove elide entirely, if we default on richtext, let people define manually plaintext with elide.
3. fix the padding in the indicator/contentItem.
4. resolve the id collision