Improving chemical descriptions and UI

[ml-evs]

From our discussions, we want to encapsulate more chemical info than just formula in our API/UI. Suggestion could be to make a new field for samples, starting materials that encapsulates possible chemical descriptions like:

class SubstanceInfo(BaseModel):
    chemform: str
    smiles: str
    composition: list[tuple[Element, float]]
    iupac_name: str

somehow these are interlinked. The UI can also provide special visualisations if certain ones are set, e.g., render 2D molecule if SMILES is available.