Added RepositorySourceInterface.php

https://git.n64.cc/nosial/ncc/-/issues/28

src/ncc/Interfaces/RepositorySourceInterface.php

@@ -0,0 +1,21 @@
+<?php
+
+    namespace ncc\Interfaces;
+
+    use ncc\Objects\DefinedRemoteSource;
+    use ncc\Objects\RemotePackageInput;
+
+    interface RepositorySourceInterface
+    {
+        /**
+         * Fetches a package and all it's dependencies from the given remote source
+         * and optionally converts and compiles it to a local package, returns the
+         * fetched package as a path to the ncc package file. This function uses
+         * a defined remote source to fetch the package or build the package from.
+         *
+         * @param RemotePackageInput $packageInput
+         * @param DefinedRemoteSource $definedRemoteSource
+         * @return string
+         */
+        public static function fetch(RemotePackageInput $packageInput, DefinedRemoteSource $definedRemoteSource): string;
+    }