feat: merge "datalayer browser" and "data browser"

[yohanboniface]

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Small big PR!

Previously, we had both a "datalayers browser" and a "data browser", now those two are merged.

The datalayers browser looked like this:

The data browser looked like this:

The new browser has two modes, an expanded mode and a condensed mode.

Expended mode, which is roughly the same as the previous data browser:

In condensed mode:

One can switch from those two mode by a button in the panel:

Once the panel is in a given mode, it will stay in this mode unless the user changes it.

The button to open the browser is now on the right of the screen (while it was on the left before), and a new "caption" button appears:

In edit mode, the browser stays, and replaces the previous box to list the layers:

Again, it can be either in condensed mode or in expanded mode:

When editing a given layer, a new "back" button appears, to go back to the browser (fix #330):