Add presubmit LFI tests

We want to add presubmit tests whenever the external LFI repos are
updated. We define all presubmit tests in system/lfi and import them
into the external/lfi repos using TEST_MAPPING's import functionality.
This allows us to update the presubmit tests in one area and all repos
affecting LFI will run the same presubmit tests.

Bug: 494581279
Test: atest --test-mapping :presubmit
Change-Id: I1c21e4a89cb7381bb697b24804de15a71bf8d516

TEST_MAPPING

diff --git a/TEST_MAPPING b/TEST_MAPPING
new file mode 100644
index 0000000..7492e83
--- /dev/null
+++ b/TEST_MAPPING
@@ -0,0 +1,7 @@
+{
+  "imports": [
+    {
+      "path": "system/lfi"
+    }
+  ]
+}
\ No newline at end of file