Add endpoint to generate JBrowse2 configs

[ctcncgr]

Add endpoint to generate a collective jbrowse2 config from a list of genus or species provided by the DSCensor API.

It would be really cool if one could create combined jbrowse2 configs for single session usage without needing to combine all of the data in the LIS-datastore.

It could cache in memory combinations created by the users until the app is restarted. The footprint of these is very small KBs at most, so could be easily loaded in memory for dumping when it needs to be served.

There are a lot of ways to approach this. I will make some examples.