issue #2344
* Add install/unintall Plugin statement
* Add show plugin statement
* Support install plugin through two ways:
* Built-in Plugin: use PluginMgr's register method.
* Dynamic Plugin: install by SQL statement, and the process:
1. check Plugin has already install?
2. download Plugin file from remote source or copy from local source
3. extract Plugin's .zip
4. read Plugin's plugin.properties, and check Plugin's Value
5. dynamic load .jar and init Plugin's main Class
6. invoke Plugin's init method
7. register Plugin into PluginMgr.
8. update meta
* Support FE Plugin dynamic uninstall process
1. check Plugin has install?
2. invoke Plugin's close method
3. delete Plugin from PluginMgr
4. update meta
* Add audit plugin interface
* Add plugin enable flags in Config
* Add plugin install path in Config, default plugin will install in ${DORIS_FE_PATH}/plugins
* Add FE plugins project
* Add audit plugin demo
The usage:
```
// install plugin and show plugins;
mysql>
mysql> install plugin from "/home/users/seaven/auditplugin.zip";
Query OK, 0 rows affected (0.05 sec)
mysql>
mysql> show plugins;
+-------------------+-------+---------------+---------+-------------+------------------------+--------+---------------------------------------+
| Name | Type | Description | Version | JavaVersion | ClassName | SoName | Sources |
+-------------------+-------+---------------+---------+-------------+------------------------+--------+---------------------------------------+
| audit_plugin_demo | AUDIT | just for test | 0.11.0 | 1.8.31 | plugin.AuditPluginDemo | NULL | /home/users/hekai/auditplugindemo.zip |
+-------------------+-------+---------------+---------+-------------+------------------------+--------+---------------------------------------+
1 row in set (0.00 sec)
mysql> show plugins;
+-------------------+-------+---------------+---------+-------------+------------------------+--------+---------------------------------------+
| Name | Type | Description | Version | JavaVersion | ClassName | SoName | Sources |
+-------------------+-------+---------------+---------+-------------+------------------------+--------+---------------------------------------+
| audit_plugin_demo | AUDIT | just for test | 0.11.0 | 1.8.31 | plugin.AuditPluginDemo | NULL | /home/users/hekai/auditplugindemo.zip |
+-------------------+-------+---------------+---------+-------------+------------------------+--------+---------------------------------------+
1 row in set (0.00 sec)
mysql> uninstall plugin audit_plugin_demo;
Query OK, 0 rows affected (0.04 sec)
mysql> show plugins;
Empty set (0.00 sec)
```
TODO:
*Config.plugin_dir should be created if missing
