Create bp2build converter for cc_shared_library

Factor out shareable code with cc_static_library

Remove `Linkstatic` field for shared cases,
because it's redundant with the rule

Bug: 198241907
Test: cc_library_shared_conversion_test.go
Test: mixed_{libc,droid}.sh
Change-Id: I5be3b66f812893bce41edb425fbd143ab22d9051
diff --git a/cc/bp2build.go b/cc/bp2build.go
index 7a98fd0..67ea70e 100644
--- a/cc/bp2build.go
+++ b/cc/bp2build.go
@@ -111,24 +111,23 @@
 	return
 }
 
-// bp2buildParseSharedProps returns the attributes for the shared variant of a cc_library.
-func bp2BuildParseSharedProps(ctx android.TopDownMutatorContext, module *Module) staticOrSharedAttributes {
+// bp2BuildParseLibProps returns the attributes for a variant of a cc_library.
+func bp2BuildParseLibProps(ctx android.TopDownMutatorContext, module *Module, isStatic bool) staticOrSharedAttributes {
 	lib, ok := module.compiler.(*libraryDecorator)
 	if !ok {
 		return staticOrSharedAttributes{}
 	}
+	return bp2buildParseStaticOrSharedProps(ctx, module, lib, isStatic)
+}
 
-	return bp2buildParseStaticOrSharedProps(ctx, module, lib, false)
+// bp2buildParseSharedProps returns the attributes for the shared variant of a cc_library.
+func bp2BuildParseSharedProps(ctx android.TopDownMutatorContext, module *Module) staticOrSharedAttributes {
+	return bp2BuildParseLibProps(ctx, module, false)
 }
 
 // bp2buildParseStaticProps returns the attributes for the static variant of a cc_library.
 func bp2BuildParseStaticProps(ctx android.TopDownMutatorContext, module *Module) staticOrSharedAttributes {
-	lib, ok := module.compiler.(*libraryDecorator)
-	if !ok {
-		return staticOrSharedAttributes{}
-	}
-
-	return bp2buildParseStaticOrSharedProps(ctx, module, lib, true)
+	return bp2BuildParseLibProps(ctx, module, true)
 }
 
 func bp2buildParseStaticOrSharedProps(ctx android.TopDownMutatorContext, module *Module, lib *libraryDecorator, isStatic bool) staticOrSharedAttributes {
@@ -178,6 +177,7 @@
 	Src bazel.LabelAttribute
 }
 
+// NOTE: Used outside of Soong repo project, in the clangprebuilts.go bootstrap_go_package
 func Bp2BuildParsePrebuiltLibraryProps(ctx android.TopDownMutatorContext, module *Module) prebuiltAttributes {
 	var srcLabelAttribute bazel.LabelAttribute