Write a solve_fermion function

[caleb-johnson]

Write a function, solve_fermion, which is meant to plug in to SQD workflows. This will largely be the same as the current solve_dice function, but this function should mimic the interface of solve_fermion in SQD.

[caleb-johnson]

Although Dice wants an active space path, we can probably take the hcore and eri and make our own active space from those integrals using the pyscf.fcidump.from_integrals function, along with the tempfile package. This will allow us to mimic the SQD solver functionality, which I prefer to taking the path to the whole active space file

Similarly, we can use tempfile to create a working directory if one isn't passed, instead of making it a required positional argument.