When a setting is injected to homepage, we now allow the setting
provider customize the background color for its icon.
If no custom bg color is provided, we fallback to existing behavior.
This behavior is only needed in homepage, because we don't have any
tinting logic in other pages so external setting providers can just
provide arbitrary icon.
Bug: 77188317
Test: robotests
Change-Id: I7d4b512fafc28537de46192026ce4bbe51b498c4
If a homepage tile is injected from external packages, we can't
control what their icons look like, so we put a generic blue circular
background to make it consistent with the other icons.
Change-Id: I2a935db37fff097ae15540262bff94efea55179a
Fixes: 69314641
Test: robotests
