Improve pressure and temperature shape checks in batch simulation

[thomasloux]

All torch-sim integrators can batch systems, allowing different temperatures and pressures per systems. But the checks are not uniformized and should also prevent ambiguities: running 3 systems and passing 3 pressures that actually correspond to pressure in x,y,z and not 3 pressures per systems. These ambiguities are not super common but a warning should be raised to force user to provide a pressure in shape (1, 3) or duplicate values to be of shape (3, 3) to remove ambiguity.
These checks should probably be run in ts.integrate, in which case for pressure, this argument should be added as a default argument.