protocol source, all about protocols and uri schemes

Add protocol.h and protocol.c containing all about libcurl's
known URI schemes and their protocol handlers (so they exist).

Moves the scheme definitions from the various sources files into
protocol.c. Schemes are known and used, even of the protocol
handler is not build or just not implemented at all.

Closes #20906

lib/http.c

@@ -4996,7 +4996,7 @@ void Curl_http_resp_free(struct http_resp *resp)
 /*
  * HTTP handler interface.
  */
-static const struct Curl_protocol Curl_protocol_http = {
+const struct Curl_protocol Curl_protocol_http = {
   Curl_http_setup_conn,                 /* setup_connection */
   Curl_http,                            /* do_it */
   Curl_http_done,                       /* done */
@@ -5017,37 +5017,3 @@ static const struct Curl_protocol Curl_protocol_http = {
 };
 
 #endif /* CURL_DISABLE_HTTP */
-
-/*
- * HTTP handler interface.
- */
-const struct Curl_scheme Curl_scheme_http = {
-  "http",                               /* scheme */
-#ifdef CURL_DISABLE_HTTP
-  ZERO_NULL,
-#else
-  &Curl_protocol_http,
-#endif
-  CURLPROTO_HTTP,                       /* protocol */
-  CURLPROTO_HTTP,                       /* family */
-  PROTOPT_CREDSPERREQUEST |             /* flags */
-  PROTOPT_USERPWDCTRL | PROTOPT_CONN_REUSE,
-  PORT_HTTP,                            /* defport */
-};
-
-/*
- * HTTPS handler interface.
- */
-const struct Curl_scheme Curl_scheme_https = {
-  "https",                              /* scheme */
-#if defined(CURL_DISABLE_HTTP) || !defined(USE_SSL)
-  ZERO_NULL,
-#else
-  &Curl_protocol_http,
-#endif
-  CURLPROTO_HTTPS,                      /* protocol */
-  CURLPROTO_HTTP,                       /* family */
-  PROTOPT_SSL | PROTOPT_CREDSPERREQUEST | PROTOPT_ALPN | /* flags */
-  PROTOPT_USERPWDCTRL | PROTOPT_CONN_REUSE,
-  PORT_HTTPS,                           /* defport */
-};