Enable load external plugins by package

[lwz9103]

mlsql enables load multiple plugins, like apps, ets and others. But, we need to specify the streaming.plugin.clzznames, if we have many plugins to load, this param will be very long.

In general, we will develop plugins in the same package for one purpose. So if mlsql can provide loading plugins by package, users can simplify the config.

[lwz9103]

Dev Design

• Add config streaming.plugin.packages

• Scan the package and load plugins in top-level

  Recursive scan sub-packages will consume a lot of time

[lwz9103]

Test Evidence

1. Add plugin lib

2. Add config in the start command

3. Use plugin ets function