Implementation of `cfp.pp.get_gene_embedding_from_esm`

Description of feature

We would like to have a function which fetches the gene embeddings, i.e.

def get_gene_embedding_from_esm(genes: List[str], ems_model: Literal["esm2", "esm3"], ..., **kwargs) -> dict[str, ArrayLike]:
    """Get the gene embedding from ESM2 or ESM3"""

• The first thing is to check whether we have gene ids or gene names. If we have gene names, we will have to convert them to gene ids first.
• Probably, we'll have some argument like representation_mode which allows to get different kinds of embeddings of the model, e.g. whether we would like to have a certain layer representation / mean repr. of different layers / etc.
• We would like the ems packages to be optional dependencies, hence only imported within the function.
• We should add tests.