Add a CLI interface to the upload-sarif action

src/repository.ts

@@ -0,0 +1,16 @@
+// A repository name with owner, parsed into its two parts
+export interface RepositoryNwo {
+  owner: string;
+  repo: string;
+}
+
+export function parseRepositoryNwo(input: string): RepositoryNwo {
+  const parts = input.split('/');
+  if (parts.length !== 2) {
+    throw new Error(`"${input}" is not a valid repository name`);
+  }
+  return {
+    owner: parts[0],
+    repo: parts[1],
+  };
+}