Add exclude_from_vendor_snapshot property, related logic

When building a vendor snapshot, the general rule the
build system uses to select a module for inclusion into
the vendor snapshot is if it's a framework module.
However, there are cases where a partner may modify the
framework module, thereby assuming control of that
module.

This change adds the exclude_from_vendor_snapshot
property allowing the partner to mark a module that
would normally be included in the vendor snapshot for
exclusion. This module is then built from source when
building the vendor image against the vendor snapshot.

Bug: 165705527
Test: m nothing
Test: build partner code against vendor snapshot
Change-Id: I6c5c15f13eeeb8f29717a4abd84b65fa72096889
diff --git a/cc/image.go b/cc/image.go
index 4daed7c..ea6f567 100644
--- a/cc/image.go
+++ b/cc/image.go
@@ -223,7 +223,7 @@
 		// We assume that modules under proprietary paths are compatible for
 		// BOARD_VNDK_VERSION. The other modules are regarded as AOSP, or
 		// PLATFORM_VNDK_VERSION.
-		if isVendorProprietaryPath(mctx.ModuleDir()) {
+		if isVendorProprietaryModule(mctx) {
 			vendorVariants = append(vendorVariants, boardVndkVersion)
 		} else {
 			vendorVariants = append(vendorVariants, platformVndkVersion)
@@ -249,7 +249,7 @@
 				platformVndkVersion,
 				boardVndkVersion,
 			)
-		} else if isVendorProprietaryPath(mctx.ModuleDir()) {
+		} else if isVendorProprietaryModule(mctx) {
 			vendorVariants = append(vendorVariants, boardVndkVersion)
 		} else {
 			vendorVariants = append(vendorVariants, platformVndkVersion)