[Assignment-7] Flake + App base

- Add Assignment-7 to flake.nix
- Implement basic framework of app
- Implement proxy subcommand (mostly)
- Implement basics of intermediary subcommand

7-SGX_Hands-on/src/app/intermediary.h

@@ -0,0 +1,23 @@
+#ifndef _APP_INTERMEDIARY_H_
+#define _APP_INTERMEDIARY_H_
+
+
+/*
+ * @brief getter for intermediary subcommand syntax string
+ *
+ * @returns null-terminated syntax string
+ */
+char* intermediary_syntax(void);
+
+/*
+ * @brief CLI implementation for the "intermediary" subcommand
+ *
+ * @param argc number of arguments with command and subcommand stripped
+ * @param argv arguments with command and subcommand stripped
+ *
+ * @returns 0 on success, else error with output on stderr
+ */
+int handle_intermediary(int argc, char** argv);
+
+
+#endif