feat: CIF handling

[RobBuchananCompPhys]

This work aims to encompass much of the existing functionality of the CIFHandler and ImportCIFDialog interfaces. It does this via passing a pointer to a CIFContext (which is a node type alias for CIFHandler) between various nodes.
Together these form a sort of CIF-node "family".

• CIFLoaderNode: Initialises a CIFContext object and reads into it the contents of a .cif file.
• CIFMolecularSpecies: Recieves and stores a CIFContext *, generating from it the detected molecular species and supercell configuration as output parameters
• CIFSuperMolecule: Recieves and stores a CIFContext *, generating from it the supercell species
• CIFPeriodicFramework: Recieves and stores a CIFContext *, generating from it the unit cell species and configuration as output parameters
• CIFAtomicOptionsNode, CIFBondingOptionsNode, and CIFNETAOptionsNode operate on the context pointer and apply various settings to it (for instance removeAtomics, useCIFBondingDefinitions, and setMoietyRemovalNeta etc.`
• SetCIFAtomGroupActivity takes the CIFContext * and allows for activation/deactivation of chosen CIFAssembly CIFAtomGroup instances.

[rprospero]

Looks clearer than I'd expected from anything with CIF attached to it. I have some general comments and a few minor suggestions, but the only major concern is establishing a FilePath type in the long term.

[trisyoungs]

I think this is a great start for the new CIF handling in Dissolve2. From looking through the nodes as they stand I think we should move away from operating on the context and passing it as a pointer, and move towards passing a proper CIFContext object around, each node making a copy of the input context, modifying it, and sending its own CIFContext as an output. If we do this then we can also have a pseudo-Configuration generated within each CIFContext at each stage of the graph.