Migrate appropriate parts of ReactJS code to discvr-components

[bbimber]

As our react code evolves, it will likely be useful to have some core code/components in a standalone monorepo with multiple npm packages, rather than living in the repo with a specific LabKey module. I created bimberlab/discvr-components, which is currently just a stub repo. We should build the basic repo structure to house multiple npm packages, and add whatever basic github actions are appropriate for CI and publishing artifacts.

Some thoughts on what might make sense to migrate here:

• The JBrowse plugins might make sense as discrete standalone packages. This is how JBrowse normally expects a plugin to work. This would make it easier to re-use them across derivatives of the Browser in different LK modules
• We might want to make a generic Utils type package, with LabKey-specific code, such as general error handling

[hextraza]

Added a bit to https://github.com/bimberlabinternal/discvr-components/issues as a starting point. In particular we should flesh out https://github.com/bimberlabinternal/discvr-components/issues/3 with anything else