frontend/node-red-dashboard: Make it easier to just preview a sample

[ethanjli]

This feature request was made by @babo989 in the 2021-01-04 software meeting.

Is your feature request related to a problem? Please describe.
For demos and educational workshops, we usually don't care about image acquisition and instead just want to focus on the objects in the camera preview stream, and maybe adjust the pump. However, depending on screen resolution it can be difficult to make the Node-RED dashboard's camera preview big enough to see things in detail, or the Optic Configuration page may be cluttered with various panels we don't want to adjust. Right now, we can just zoom in on the page - but this tends to make it hard to access the UI elements for adjusting the pump.

Describe the solution you'd like
There should either be a separate "sample preview" page with just a larger camera preview and pump control, or there should be a way to adjust the "Optic Configuration" page to enlarge the camera preview and collapse any unnecessary panels, while still keeping relevant panels easy to access.

It could also be nice to provide a way to adjust the actual resolution of the camera preview so that it looks nicer on large high-resolution screens (e.g. 4K) - right now that is done by manually editing the raspimjpeg.conf file

Describe alternatives you've considered
(see above for the list of alternatives)

Additional context
#79 will replace raspimjpeg with picamera2, so we should probably hold off on implementing a UI element to increase the resolution of the camera preview until after completion of #79, since that requested feature might take quite a bit of work.

[ethanjli]

@BiyouS Do you think your Node-RED dashboard will address this feature request (e.g. if your new design already makes the camera preview stream larger on the "Sample Preview" page)? If so, I will add you as an assignee on this issue.