Consolidate the code to resolve a deapexer module dependency.

It will get more logic in upcoming CLs.

Add a property to DeapexerInfo for the APEX name, for use in error
messages.

Test: m nothing
Bug: 192006406
Change-Id: I957f3df8b34543a38cde38768dac93e78132d672

apex/prebuilt.go

@@ -631,10 +631,6 @@ func createDeapexerModuleIfNeeded(ctx android.TopDownMutatorContext, deapexerNam
 	)
 }
 
-func deapexerModuleName(baseModuleName string) string {
-	return baseModuleName + ".deapexer"
-}
-
 func apexSelectorModuleName(baseModuleName string) string {
 	return baseModuleName + ".apex.selector"
 }