Add METADATA to contexthub: Apache2+BSD+LLVM+MIT=NOTICE

Bug: 68860345
Bug: 69058154
Bug: 151953481

Test: no code changes
Change-Id: I31d64fdd30f7242b854278ec7b061934725e56c2
diff --git a/METADATA b/METADATA
new file mode 100644
index 0000000..d97975c
--- /dev/null
+++ b/METADATA
@@ -0,0 +1,3 @@
+third_party {
+  license_type: NOTICE
+}