Fractional coordinates not scaled in LAMMPS engine

**Description of the error**

The LAMMPSEngine.convert_trajectory method supports a keyword argument "scaled_positions":
https://github.com/MDMCproject/MDMCv0.2_pilot/blob/f1e7a6399e1fb0dbd8600914436962feb951523d/MDMC/MD/engine_facades/lammps_engine.py#L494
If fractional coordinates are used in the LAMMPS trajectory, labels 'xs', 'ys', 'zs' will be used in the trajectory file. To read such a file, it is necessary to set scaled_positions=True when calling this method, or the conversion will fail.

**Describe the expected result**
The convert operation should find the positions in the trajectory, scale them by the dimensions of the simulation box, and send them to the CompactTrajectory object.

**Describe the actual result**
The convert operation finds the fractional coordinates and sends them to the CompactTrajectory without scaling, resulting in all the atom positions being between 0 and 1 Angstroms.

**Suggested fix**
The additional operation of multiplying the coordinates by box dimensions needs to be added.

**Additional details**
This is not an urgent problem, since a normal MDMC run produces trajectories with absolute positions instead of fractional.