Improve diagnostic logging in PluginPage.processEvents

Diagnostics around

org.hippoecm.frontend.PluginPage#processEvents

goes no deeper than this method. The task does three things which may be improved with diagnostics. Models and services are refreshed and events are processed. Beyond that more fine grained logging may be desirable but that requires investigation.

See also dev list thread:

CMS diagnostics: time missing

Where Woonsan makes some suggestions for improved logging:

If we'd fix that, I'd like to suggest the following, just for the record:

• Add IPluginFactory interface and make it a cms service, which is configured separately. Let PluginManager refer to the service through the interface instead of creating PluginFactory directly.
• Let the PluginFactory impl as a new service class have its as-is logics.
• Let PluginManager wraps the IPluginFactory instance by a delegating IPluginFactory for HDC loggings.