Updated CRT library, test process, EventLoopGroup API updates (#16)

* Updated to latest aws-crt-ffi, updated EventLoopGroup/options init

* Removed test-ci target, just use test for everything now

* Added event_loop_group API to CRT/stubs

* Removed headers (all generated) from format-check

* Added the ability to force extension vs FFI

* make test will now trigger composer run test/phpunit, and force tests with both FFI and extension

* Updated builder version, removed redundant php7 test run

* Removed type annotations that anger php5, limited backends on php5

src/AWS/CRT/Internal/Extension.php

@@ -20,7 +20,7 @@ final class Extension {
      * same name with the supplied arguments. Argument type hinting and checking
      * occurs at the CRT wrapper.
      */
-    function __call(string $name, $args) {
+    function __call($name, $args) {
         return call_user_func_array($name, $args);
     }
 }