Simplify logging configuration

[mrossinek]

What is the expected behavior?

Qiskit Aqua used to provide some simplified means of enabling Python's internal logging for certain modules:

https://github.com/Qiskit/qiskit-aqua/blob/main/qiskit/chemistry/_logging.py#L30-L37

I believe, Qiskit Nature would benefit a lot from a similarly simple configuration setting.
#406 is adding a qiskit_nature.settings object which permits simple global configuration settings. Based on another setting, logging could be configured in a similar manner to how it used to be done in Aqua.

Here are some ideas as to what logging options should be possible (for now at least):

• set all qiskit_nature logging to a given level
  • (optionally) specify a list of pairs matching logging levels to submodules (not required for now imo)
  • (optionally) support arbitrary logger names in the above list (could be used to easily control logging of other modules like Qiskit Terra, PySCF, etc.)
• default to a StreamHandler which logs to sys.stdout
  • (optionally) support custom handler addition (FileHandler, RotatingFileHandler, etc.)
  • (optionally) support custom Formatter

More Aqua-related references:

• https://github.com/Qiskit/qiskit-aqua/blob/main/qiskit/aqua/_logging.py