Add ability to use JBrowse 2 config file

[teresam856]

We can currently create a config in two ways

1. create('view', genome='hg38')
2. create("config") or create("config", conf={bulk config})

We want to be able to create a view from a path to a jb2 config 3) create("jb2config", path="path/to/jb2/config.json")

We would need to complete the converter/parser which would read and format a jb2 config file into the appropriate config to pass to jbrowse react linear genome view.