Blender Git Loki

Asset Browser: UI polish for the asset metadata sidebar

* Show asset path in a (read only) text button. Makes it possible to see the
full path in the tooltip, brings support for copying the path and integrates
better with the sourrounding layout. Previous label needed lots of space to
show the full path without clipping.
* Remove "Details" panel, it only contained one item (description). That is
moved next to the name and asset path button.
* Use property split layout for name source and description buttons. Now that
there are multiple buttons, it's better to have a label for them.
* Always show operators for asset previews, just gray them out if not
applicable instead of hiding. Keeps the layout consistent and graying out is
less confusing than hiding UI elements.