Blender Git Loki

Fix compile error of asset library test on Windows

The `filesystem::path::c_str()` function returns the path in the native
string format, which is `wchar` on Windows. Instead use the one that
does a conversion to `std::string` if needed.

Correct name of catalog-tree item child container alias

This used to be a set, now it's a map.

Avoid unnecessary allocations in unit test

Add and use initial UI Tree-View API

This adds a simple to use API to implement custom tree views. This
should make adding tree like layouts much easier & cleaner. Plus, it
should become easier to mange UI state (once I've done some more
additions).
Another goal for this was separating UI code better from the data,
currently we often have to add UI state information to the data (we may
still have to do this in some cases for file writing).

Idea is to let API users implement a custom tree-view class, that
inherits from `uiAbstractTreeView` and implements its `build_tree()`
function to add tree items. Each such item has a custom type, that
defines how its tree row is drawn. For that, another class can be added,
inheriting from `uiAbstractTreeViewItem` and implementing its
`build_row()` function. But this also adds `uiBasicTreeViewItem` which
is just a tree-row with an icon and a label, for convenience. More such
common tree-view item types can be added.

I'm quite happy with how this turned out eventually. This could work!

The resulting UI should look identical to the one before this commit.
Only internals changed (drastically).

Basic support for creating catalogs from the UI

To the right of each catalog, the UI shows a '+' button now. It creates
a catalog (simply named "Catalog" for now) inside this parent catalog.
This change is written to the asset libraries catalog defintion file
immediately.
Adding multiple catalogs on the same level will cause errors currently,
since then you have multiple catalogs on the same level named "Catalog".
We'll have to ensure uniqueness there.

I think we should immediately enable renaming after creating a new
catalog, like we do it for creating new files in the File Browser.

Minor tweaks

* Avoid unnecessarily specifying button width.
* Remove left padding from items without icon, looks better that way.

Very basic tree drawing in the Asset Browser sidebar

Draws the catalogs in the Asset Browser sidebar with some dummy icons.
Also adds an "All" and a "Unassigned" item. Besides hover feedback,
interaction is not working yet.

Also removes the categories UI and makes sure all assets are drawn
always. Filtering by catalog needs to be implemented still.

Add tests for catalog tree

Removes the printing of the catalog tree. Also adds and tests a function
to get the full catalog path from a tree item.

Simplify catalog tree creation using std::map

By using std::map with the catalog-component name as key simplifies
creation quite a bit. Generally it seems like the most appropriate
container for storing children in the tree.

Merge branch 'master' into temp-asset-browser-catalogs

Initial tree structure to load catalogs into

See T90608 and the basic design in T90066.

This tree structure will be needed for adding the UI. It's unclear how
much of the catalog backend will change still. Some design questions
were raised that need further discussion.

Use `ghc::filesystem` as platform compatible replacement for `std::filesystem`

Previous commit merged the `temp-cpp-ghc-filesystem` branch into this, now we
can actually use this replacment. This way the branch can be compiled on macOS.

Merge branch 'temp-cpp-ghc-filesystem' into temp-asset-browser-catalogs

Dependencies: Drop-in replacement for std::filesystem (in extern/)

Introduces the ghc::filesystem library as a (leight weight, header
only) drop-in replacement for std::filesystem. The latter can't be
used on the minimum macOS version we support. Once that changes, we can
switch to using std::filesystem directly.

Part of T90379.

* Add ghc::filesystem to extern/ as platform compatible replacement for
std::filesystem.
* Add Windows specific code to avoid issues with including Windows.h.
* Add blender::bli::filesystem as alias for ghc::filesystem. That should make
the ghc -> std transition easier later on since we can just change this
alias. Also makes it easy to switch between the two at compile time.

Merge branch 'master' into temp-asset-browser-catalogs

Merge branch 'master' into temp-asset-browser-catalogs

Asset Catalogs: change default catalog definition file name

Change the default catalog definition file name from
"single_catalog_definition_file.cats.txt" to "blender_assets.cats.txt".

Cleanup: use same parameter name in declaration & definition

Asset Catalogs: clean up catalog paths before using them

Clean up paths by trimming whitespace and separators
`/path/to/something ` ? `path/to/something`.

Asset Catalogs: allow adding new catalogs

New catalogs can be added with `AssetCatalogService::create_catalog()`.
It only requires the catalog path, and convert that into a suitable
catalog ID itself. It is intended that artists won't have to bother with
assigning catalog IDs, and that editing those is more of an advanced
feature.

Adding a catalog will automatically save the catalog definition file to
disk.