Sometimes it is necessary to pass additional data through generic UI entities,
to specific implementations. For example to pass additional options to panel
polling & drawing when instantiating a panel through its panel type. Or storing
additional data in a button, without hardcoding it in the button struct/class.
Passing data via context is a simple solution to this, however so far this only
works using hardcoded context queries or RNA pointers. For passing arbitrary
strings we've used workarounds like creating an RNA type to wrap it already.
For example `RNA_AssetCatalogPath`, which is used to dynamically populate menu
items based on an asset catalog path, via a generic menu type.
type instantiation. This makes it possible to invoke specific asset shelves as
popover panels.
Idea is simply to let `bContextStore` entries hold copies of the string (as
`std::string`), avoiding lifetime issues. Context APIs are extended to support
setting/querying strings via a context member name.
Pull Request: https://projects.blender.org/blender/blender/pulls/122113
2fbf206491