Support more data formats & options (e.g., FASTA, GFF, etc)

[sehilyi]

Since the range of data types we supports is closely related to the usability of Gosling, we need to support additional data types that we discussed. These include

• #583
• #184
• #764
• https://github.com/gosling-lang/gosling.js/issues/573
• Support loading multiple data fetchers in a single track (I somehow cannot find a dedicated issue).

Additionally, we can explore ways to support other cloud services:

• Google Cloud in IGV: https://googlegenomics.readthedocs.io/en/latest/use_cases/browse_genomic_data/igv.html