Handle prebuilt vs source selection in bp2build

Test: enable mainline modules build from prebuilts and build
Bug: 300640274
Change-Id: Ib1d6bbca7e0ab459515d3cf6378741e8368e7327

android/mutator.go

@@ -55,6 +55,7 @@ func registerMutatorsForBazelConversion(ctx *Context, bp2buildMutators []Registe
 		// TODO(b/165114590): this is required to resolve deps that are only prebuilts, but we should
 		// evaluate the impact on conversion.
 		RegisterPrebuiltsPreArchMutators,
+		RegisterPrebuiltsPostDepsMutators,
 	},
 		bp2buildMutators...)