MDL-31625 fix multiple global search-replace issues

Includes following fixes:
* support for MS SQL Server
* optional trimming of of oversized VARCHAR fields
* conversion to forms library
* full localisation
* other cleanup

lib/dml/pgsql_native_moodle_database.php

@@ -1216,6 +1216,16 @@ class pgsql_native_moodle_database extends moodle_database {
         return $positivematch ? '~*' : '!~*';
     }
 
+    /**
+     * Does this driver support tool_replace?
+     *
+     * @since 2.6.1
+     * @return bool
+     */
+    public function replace_all_text_supported() {
+        return true;
+    }
+
     public function session_lock_supported() {
         return true;
     }