Instead of using $group->insert(....)->addComponent() we can define
our own small SingleMenuEntry that defines a standard menu entry with
a label and one icon. The icon name and tracking code by default will
be the same as the menu entry name.
Changes:
- introduced SingleMenuEntry class
- updated Definitions class to use new entry instead of using old
MenuEntry class
- changed the Contributions meny entry name to match icon/tracking
This should simplify code a bit, thanks to this approach we should be
able to remove the Definitions class in some future and keep building
MenuElements in the builders.
Bug: T221792
Change-Id: I1f145e8cd173b72b01a145b2dba3704593f17ab7
