Implement PYMAPDL_DEBUG env var

[germa89]

This env var will:

• change MAPDL gRPC verbosity to 5.
• activate PyMAPDL APDL logging
• Activate PyMAPDL debug to stdout and file

[germa89]

It will be also nice to have something like:

from ansys.mapdl import core as pymapdl
pymapdl.DEBUG = True

which does the same stuff.

[germa89]

Related to #2822 #2703

[germa89]

Also, we should extend more the infor when failing under these env var. For example, making sure you are always printing the MAPDL working directory.

Special care should be put into the MAPDL starting part.

[germa89]

ideally we would also like to have something like:

pymapdl --debug on

so after that the debug prints are available until:

pymapdl --debug off

Something like that. We should then rely on the config file.

[germa89]

We should take advantage of #3596