[BREAKING CHANGE] Use registry for tool group types

Per the comment, so they can be overridden.

Change-Id: I10e5d256ccf9db33be428bcd47db160ecf3a9632
Basic toolbar demo

Change-Id: Idc16993c93cece151ffd4ed699cfda8891f66c35
Styling for disabled toolgroups

Change-Id: I3599315f7221bd50866457030f890ef139db32e5
Force visible label for MenuToolGroups

A completely emptry string hides the label, which makes the
centre of the MenuToolGroup unclickable when empty.

Change-Id: I57f9e4ec1532334b252751ad7ae82df3d4c5c1b3
Merge "[BREAKING CHANGE] Use registry for tool group types"
Merge "Basic toolbar demo"
Merge "Styling for disabled toolgroups"
Merge "Force visible label for MenuToolGroups"