[Refactor](dialect) Add sql dialect converter plugins (#28890)

The current logic for SQL dialect conversion is all in the `fe-core` module, which may lead to the following issues:
- Changes to the dialect conversion logic may occur frequently, requiring users to upgrade the Doris version frequently within the fe-core module, leading to a longer change cycle.
- The cost of customized development is high, requiring users to replace the fe-core JAR package.

Turning it into a plugin can address the above issues properly.

fe/fe-common/src/main/java/org/apache/doris/common/Config.java

@@ -2397,6 +2397,9 @@ public class Config extends ConfigBase {
             "Whether to enable the function of getting log files through http interface"})
     public static boolean enable_get_log_file_api = false;
 
+    // This config is deprecated and has not taken effect anymore,
+    // please use dialect plugin: fe_plugins/http-dialect-converter for instead
+    @Deprecated
     @ConfField(description = {"用于SQL方言转换的服务地址。",
             "The service address for SQL dialect conversion."})
     public static String sql_convertor_service = "";