Add CLI fixers for incorrectly static-scale-/node-optimized grids

[cschwan]

Monte Carlo integrators use Grid::fill to insert phase-space events into an interpolation grid, and sometimes it can happen that for some (bin, order, channel) combination exactly a single phase-space point is inserted. This has the consequence that when calling Grid::optimize, a specific optimization (OPTIMIZE_NODES, which in PineAPPL 0.x is called STATIC_SCALE_DETECTION) undoes the interpolation. This isn't a problem in itself, but when trying to export grids to a different format, these formats don't understand the optimized subgrids.

To fix the problem, we need to reinterpolate these subgrids; this breaks down to solving the following problems:

1. Detecting the affected subgrids. This becomes a somewhat difficult problem if the affected subgrid was merged with other subgrids; in this situation parts of the subgrid is OK, the other part is not. The difficulty then lies in detecting the problematic part.
2. Split off the problematic parts of the subgrid and
3. reinterpolate it.

In PineAPPL 0.x this affected only scales, since PineAPPL 1.x this also happens for parton momenta, because PineAPPL 1.x interpolates/optimizes kinematic variables blindly of the their type.

A published and affected grid is pinejet-cms-z0-arxiv-1310.7291.

See also #358.