Allow for multiple drop_dim URL parameters

[j08lue]

Closes #3

• Made the drop_dim parameter a list
• Parsed it as a list
• Checked type consistency throughout references
• Adjusted tests

[j08lue]

The Tiler now returns, but not sure the result is as expected yet: http://127.0.0.1:8000/xarray/tiles/0/0/0.png?scale=1&url=s3%3A%2F%2Fukri-eodh-hazard-indicators-public%2Fcmip6-dd-28%2Fcubified%2Fdegree_days_2030.zarr&variable=degree_days&drop_dim=gcm%3DACCESS-CM2&drop_dim=scenario%3Dssp126&drop_dim=temperature%3D28.0&rescale=3300,3700&colormap_name=viridis 🤔

[ciaransweet]

developmentseed/titiler#1111 this is actually being added into the root titiler repo 👀 🎉

[j08lue]

Now it's a question how the enhancement made in TiTiler would make it into this repo here, since it is not even a fork.

I think the recommended way to build the EODH tiler would actually be to create a custom application that imports TiTiler constructs. Something like the application package only https://github.com/EO-DataHub/titiler-new/tree/main/src/titiler/application/titiler/application, I guess.