Moved Common HTTPS Initialization Logic in a common file

sunshine/httpcommon.h

@@ -0,0 +1,7 @@
+namespace http{
+  void init(std::shared_ptr<safe::signal_t> shutdown_event);
+  int create_creds(const std::string &pkey, const std::string &cert);
+  std::string read_file(const char *path);
+  int write_file(const char *path, const std::string_view &contents);
+  extern std::string unique_id;
+}