In the past, when we want to modify some BE configs, we have to modify be.conf and then restart BE.
This patch provides a way to modify configs in the type of 'threshold', 'interval', 'enable flag'
when BE is running without restarting it.
You can update a single config once by BE's http API: `be_host:be_http_port/api/update_config?config_name=new_value`
Support BE plugin framework, include:
* update Plugin Manager, support Plugin find method
* support Builtin-Plugin register method
* plugin install/uninstall process
* PluginLoader:
* dynamic install and check Plugin .so file
* dynamic uninstall and check Plugin status
* PluginZip:
* support plugin remote/local .zip file download and extract
TODO:
* We should support a PluginContext to transmit necessary system variable when the plugin's init/close method invoke
* Add the entry which is BE dynamic Plugin install/uninstall process, include:
* The FE send install/uninstall Plugin statement (RPC way)
* The FE meta update request with Plugin list information
* The FE operation request(update/query) with Plugin (maybe don't need)
* Add the plugin status upload way
* Load already install Plugin when BE start
