Allow searching for columns in the perspective_viewer column chooser

[msturdikova]

As a user I want to easily find a column of interest in the perspective viewer column chooser in order to move it around or hide it from the view.

Currently the visible columns define the order the columns are displayed in the grid. It there is a large number of columns it is hard to find the column of interest and then move it around or hide it.

[texodus]

<perspective-viewer> has a few accessibility features around large columns sets:

• As the column selection UI is just plain HTML, ctrl-f (or your platforms text search of choice) will scroll matching column names into view and highlight already.
• Column names are sorted by type & alphabetically, or in user-defined order (in the case of selected columns).
• The column selector itself is responsive to the dimensions of <perspective-viewer>, in order to accommodate small or oddly proportioned spaces.

I'd also point out that if the number of visible columns is so large as to make finding them difficult, then this difficulty must apply equally to the data grid itself - so the obvious solution is to only select the columns you want to see (shift-click will deselect all columns quickly).

In lieu of other specific suggestions for improvement, I will close for now. Feel free to open a PR with specific enchancements, or an issue if you feel this warrant more discussion.

[aszenz]

@texodus

shift-click will deselect all columns quickly

This is such a useful thing to know, i feel like perspective viewer is really designed for power users's but the initial learning curve is a bit steep. I would like to document more such keyboard shortcuts, is their a page in the docs already?