Rework config to support absence of label and icon in CustomTile

Config would now be provided as a separated entity in a map tileSpec to
QSTileConfg. QSTileViewModelFactory uses provided tileSpec to get a valid
config from QSTileConfigProvider.

QSTIleConfigProviderTest ensures all the configs are injected for a
correct tile spec.

Bug: 299908705
Test: atest QSTielViewModelInterfaceComplianceTest
Test: atest QSTileConfigProviderTest
Flag: LEGACY QS_PIPELINE_NEW_TILES DISABLED
Change-Id: I87ae3223e9451b66b03ac732d4d598a6196203b5