Quantum ESPRESSO: nscf/bands, md and ph.x phonons #153

Split off from #58, which is closed: Quantum ESPRESSO was verified live against pw.x 6.7 (functionals, smearing, vc-relax, stress/pressure panel). VASP and SIESTA were declared out of scope in the 09-21 priority update.

What QE still lacks:

• nscf / bands: a second run reusing the first's charge density. This does not fit ECCE's one-input/one-output calc model, so it needs a design decision first.
• md: molecular dynamics runtype.
• Phonons: ph.x is a separate executable, so it needs its own launch path.