Allow setting VSI credentials when loading OGR/GDAL layers (Request in QGIS)

[qgis-bot]

Request for documentation

From pull request qgis/QGIS#57826
Author: @nyalldawson
QGIS version: 3.40

Allow setting VSI credentials when loading OGR/GDAL layers

PR Description:

This PR exposes the VSI credential options for user control when adding OGR vector/GDAL raster layers from the Data Source Manager, eg:

The underlying provider changes were discussed in qgis/QGIS#57801. When credential options are found in a layer's URI, we use GDAL's VSISetPathSpecificOption to set the credential option for that VSI driver and bucket.

This allows per-vsi driver & bucket credentials for layers, whereas other approaches (like environment variable setting) force a single set of credentials to be used for an entire QGIS session. (And are difficult for users to set)

I've also taken the opportunity to cleanup a bunch of code relating to how VSI protocols are exposed in GUI, and how GUIs for GDAL configuration options are dynamically created.

Requires GDAL 3.5+

Commits tagged with [need-docs] or [FEATURE]