Expose verbosity setting via qcshema API

[jthorton]

Is your feature request related to a problem? Please describe.

It would be very useful to be able to set the verbosity via a keyword in the qcshema interface. Running many xtb calculations in parallel for a prolonged period currently causes the output to leak to the terminal and eventually crash with an error caused by having too many open files.

Describe the solution you'd like

Change the qcschema interface to accept a verbosity keyword with options corresponding to the options here which then sets the verbosity of the calculation. If the verbosity is muted we can then avoid creating a temporary file as having too many of these causes the error.

Describe alternatives you've considered

Additional context

I can confirm that manually setting the verbosity to VERBOSITY_MUTED and removing the creation of the temporary file avoids the error.

[jthorton]

I am also more than happy to contribute this small change.