Calculator with no parameters and null valued parameters

It should be possible to specify a calculator without any parameters. Example: the EMT calculator.

About the background of this issue: it is necessary for solving https://git.scc.kit.edu/virtmat-tools/vre-language/-/issues/113 (see MR https://git.scc.kit.edu/virtmat-tools/vre-language/-/merge_requests/79) where the tests should evaluate a property for a structure with constraints. Optimally, the calculator should be ASE internal (not external Python or other proprietary calculator).

A workaround is to specify calc = Calculator emt ((restart: false)) as all ASE calculators have the restart parameter.