Add Platform_sdk_version_or_codename variable

1. Added a new product variable Platform_sdk_version_or_codename;
2. This variable is used to support the logic in the Android.bp file
when either the Platform_sdk_version or the Platform_sdk_codename is
used.

Bug: 195986342
Test: m CtsThemeHostTestCases (the module where the product variable is
used)
Test: TreeHugger

Change-Id: I6b952ce47fd4adc280aa3c7ef4185487558af9bc

android/variable.go

@@ -42,6 +42,10 @@ type variableProperties struct {
 			Cflags  []string
 		}
 
+		Platform_sdk_version_or_codename struct {
+			Java_resource_dirs []string
+		}
+
 		// unbundled_build is a catch-all property to annotate modules that don't build in one or
 		// more unbundled branches, usually due to dependencies missing from the manifest.
 		Unbundled_build struct {
@@ -164,6 +168,7 @@ type productVariables struct {
 	Platform_version_name                     *string  `json:",omitempty"`
 	Platform_sdk_version                      *int     `json:",omitempty"`
 	Platform_sdk_codename                     *string  `json:",omitempty"`
+	Platform_sdk_version_or_codename          *string  `json:",omitempty"`
 	Platform_sdk_final                        *bool    `json:",omitempty"`
 	Platform_version_active_codenames         []string `json:",omitempty"`
 	Platform_vndk_version                     *string  `json:",omitempty"`