urlapi: cleanups

- move host checks together
- simplify the scheme parser loop and the end of host name parser
- avoid itermediate buffer storing in multiple places
- reduce scope for several variables
- skip the Curl_dyn_tail() call for speed
- detect IPv6 earlier and skip extra checks for such hosts
- normalize directly in dynbuf instead of itermediate buffer
- split out the IPv6 parser into its own funciton
- call the IPv6 parser directly for ipv6 addresses
- remove (unused) special treatment of % in host names
- junkscan() once in the beginning instead of scattered
- make junkscan return error code
- remove unused query management from dedotdotify()
- make Curl_parse_login_details use memchr
- more use of memchr() instead of strchr() and less strlen() calls
- make junkscan check and return the URL length

An optimized build runs one of my benchmark URL parsing programs ~41%
faster using this branch. (compared against the shipped 7.88.1 library
in Debian)

Closes #10935

lib/url.c

@@ -2568,29 +2568,13 @@ CURLcode Curl_parse_login_details(const char *login, const size_t len,
   size_t plen;
   size_t olen;
 
-  /* the input length check is because this is called directly from setopt
-     and isn't going through the regular string length check */
-  size_t llen = strlen(login);
-  if(llen > CURL_MAX_INPUT_LENGTH)
-    return CURLE_BAD_FUNCTION_ARGUMENT;
-
   /* Attempt to find the password separator */
-  if(passwdp) {
-    psep = strchr(login, ':');
-
-    /* Within the constraint of the login string */
-    if(psep >= login + len)
-      psep = NULL;
-  }
+  if(passwdp)
+    psep = memchr(login, ':', len);
 
   /* Attempt to find the options separator */
-  if(optionsp) {
-    osep = strchr(login, ';');
-
-    /* Within the constraint of the login string */
-    if(osep >= login + len)
-      osep = NULL;
-  }
+  if(optionsp)
+    osep = memchr(login, ';', len);
 
   /* Calculate the portion lengths */
   ulen = (psep ?