GaussMP patch

Comprehensive GaussMP patch with workarounds for LHCBGAUSS-1409, LHCBGAUSS-1779, LHCBGAUSS-1780, LHCBGAUSS-1785, LHCBGAUSS-1786.

I am sending this as an AppConfig MR as discussed with @dmuller and @gcorti. The patch uses a Gaudi hack which I have discussed also with @clemenci. This may eventually be used to submit multi-core simulation jobs via LHCbDIRAC as discussed with @fstagni.

I have tested that this works on Gauss v53r1, v52r2, v52r0, v51r0. On Gauss v53r0 there is no workaround possible for GaussMP as discussed in LHCBGAUSS-1780. This may also work on Gauss v53r2 and the nightlies, but these versions are affected by another issue LHCBGAUSS-1781 which makes GaussMP unusable (crash).