[WIP] Modern lifecycle + Ownership

[lalitb]

Ongoing PR, not yet for review.
Included changes

• Deprecate shared global state (the LogManager instance that is not really an instance).
• Return unique_ptr for ILogManager.

[mkoscumb]

This probably needs to go as well

[mkoscumb]

Really all the static methods

[lalitb]

Yes, I am trying to see if we can make LogManager as instance of LogManagerBase instead of global static, and then make all these methods as non-static. Though LogConfiguration is still a concern here, as it is difficult to create deep copy of it (as it can contain void * as the config value).