MDEV-34716 Allow arbitrary options in CREATE SERVER

The existing syntax for CREATE SERVER

CREATE [OR REPLACE] SERVER [IF NOT EXISTS] server_name
    FOREIGN DATA WRAPPER wrapper_name
    OPTIONS (option [, option] ...)

option:
  { HOST character-literal
  | DATABASE character-literal
  | USER character-literal
  | PASSWORD character-literal
  | SOCKET character-literal
  | OWNER character-literal
  | PORT numeric-literal }

With this change we have:

option:
  { HOST character-literal
  | DATABASE character-literal
  | USER character-literal
  | PASSWORD character-literal
  | SOCKET character-literal
  | OWNER character-literal
  | PORT numeric-literal
  | PORT quoted-numerical-literal
  | identifier character-literal}

We store these options as a JSON field in the mysql.servers system
table. We retain the restriction that PORT needs to be a number, but
also allow it to be a quoted number, so that SHOW CREATE SERVER can be
used for dumping. Without an accompanied implementation of SHOW CREATE
SERVER, some mysqldump tests will fail. Therefore this commit should
be immediately followed by the one implementating SHOW CREATE SERVER,
with testing covering both.

mysql-test/suite/funcs_1/r/is_table_constraints_mysql.result

@@ -30,6 +30,7 @@ def	mysql	PRIMARY	mysql	proc	PRIMARY KEY
 def	mysql	PRIMARY	mysql	procs_priv	PRIMARY KEY
 def	mysql	PRIMARY	mysql	proxies_priv	PRIMARY KEY
 def	mysql	Host	mysql	roles_mapping	UNIQUE
+def	mysql	Options	mysql	servers	CHECK
 def	mysql	PRIMARY	mysql	servers	PRIMARY KEY
 def	mysql	PRIMARY	mysql	tables_priv	PRIMARY KEY
 def	mysql	PRIMARY	mysql	table_stats	PRIMARY KEY