Allow making linear-genome-view have a certain "set height" instead of unbounded height

[cmdcolin]

this has been requested by people who embed the linear genome view as it can be odd for a view to just be small height to start, and then occupy a large area as more tracks are added. the alternative is sort of jbrowse 1-y...it has a set height, and then the overflow just makes a per view scrollbar

might be a setting that could apply for floating views also

how to determine the exact behavior is a little unknown. it could be configured by user in react-linear-genome-view for example, it could be something like 100vh (full screen height) which is the jbrowse-web/@jbrowse/react-app solution, or maybe a little less....etc.

potentially, this approach could be an alternative or re-consideration to the position sticky PR #4237