Result of meshes_join does not maintain face (vertex/edge) attributes

# Feature Request

As a designer, I want different faces in a compas mesh to have different attributes (e.g. based on function or material or...) so that e.g. further subdivision can be dependant on this attribute.

## Details

**Is your feature request related to a problem? Please describe.**
The current implementation of `meshes_join` ([here](https://github.com/compas-dev/compas/blob/master/src/compas/datastructures/mesh/join.py#L49)) completely disregards any attributes.

**Describe the solution you'd like**
Where the [faces get added](https://github.com/compas-dev/compas/blob/master/src/compas/datastructures/mesh/join.py#L75) to the new mesh, not only take into account vertex keys but also eventual existing attributes.

**Describe alternatives you've considered**
Alternative (if it is just for e.g. rendering), individual meshes can be exported and assembled again in the rendering software.