Add experimental option to target Java 17

Bug: 233029164
Test: EXPERIMENTAL_TARGET_JAVA_VERSION_17=true \
      EXPERIMENTAL_USE_OPENJDK17_TOOLCHAIN=true m
Change-Id: I80a9ba9eb356a460c1036e711e793c2ca6620f53

java/sdk.go

@@ -57,6 +57,12 @@ func defaultJavaLanguageVersion(ctx android.EarlyModuleContext, s android.SdkSpe
 		return JAVA_VERSION_8
 	} else if sdk.FinalOrFutureInt() <= 31 {
 		return JAVA_VERSION_9
+	} else if ctx.Config().TargetsJava17() {
+		// Temporary experimental flag to be able to try and build with
+		// java version 17 options.  The flag, if used, just sets Java
+		// 17 as the default version, leaving any components that
+		// target an older version intact.
+		return JAVA_VERSION_17
 	} else {
 		return JAVA_VERSION_11
 	}