Added test-ffi target, use it in CI (#9)

* Added test-ffi target, use it in CI

* Added clang-format config, fixed RETURN_STRING API mismatch

* Skip installing php and packages on the PHP docker images

* Removed al2 job that was never going to work, and compiler tests

* Fixed basic test for extension loading

* Cleaned up lib structure, fixed tests

* use test-ci target to conditionally test in GitHub

* Use v0.8.1 of builder

builder.json

@@ -32,6 +32,6 @@
         "NO_INTERACTION": "1"
     },
     "test_steps": [
-        ["make", "test"]
+        ["make", "test-ci"]
     ]
 }