This replaces the plain texture selector with a proper TemplateID,
resulting in buttons to add a new texture if none is there yet, and if
there is one, there will be the usual conveniece buttons to add a fake
user, create single user copies, ..., as well as the button to go to the
textures tab in the Properties Editor for more fine-grained control over
the texture.
Fixes#126856
Pull Request: https://projects.blender.org/blender/blender/pulls/126890
d1f0084a33