Add AppFunctions Sidecar

Test: atest CtsAppFunctionTestCases
Flag: NONE sidecar library (non platform)

Change-Id: I2f8af326a2852314ab4ed9b54166024a8888dc63
diff --git a/libs/appfunctions/api/removed.txt b/libs/appfunctions/api/removed.txt
new file mode 100644
index 0000000..d802177
--- /dev/null
+++ b/libs/appfunctions/api/removed.txt
@@ -0,0 +1 @@
+// Signature format: 2.0