Plan for updating data viewer

[BECATRUE]

Feature you want to implement

As @kangz12345 suggested, we need to update data viewer for supporting remote H5 file, dataset list viewer, table viewer, etc.

For this, I separated them into three sub-projects below:

• Explorer to show dataset list (Like artiq-dashboard data viewer)
  Implement dataset list viewer #231
• Table viewer to show a specific dataset (Not limited to table viewer only; may be extended further later)
• To support showing remote H5 file

Additional context

The overall arrangement is as below.

[BECATRUE]

Please check this plan! @kangz12345

[kangz12345]

I think we should re-design the whole structure, instead of extend the current version.
For example, one selects a dataset, then chooses the viewer type to visualize the dataset (e.g., plot style or table) and configure it (which axes to show).

[BECATRUE]

Oh, I see. Then, I will do that.