[FEAT] Parallelized plugin startup

[mattae]

Is your feature request related to a problem? Please describe.
When there are many plugins in the system, it could take a lot of time to start them all up. Usually, this time is the sum of the startup time of each plugin, even when there is no dependency among the plugins

Describe the solution you'd like
The doStartPlugins method of SpringBootPluginManager loops serially to start up the plugins. This method could be modified to start all non-dependent plugins at each instance

Describe alternatives you've considered
None

Additional context
None