Using the attribute name semantics proposed in T97452,
move the `ME_HIDE` flag from mesh vertices, edges, and
faces to boolean attribute layers.
Now the relevant data is stored in three generic boolean
attribute layers, `.hide_vert`, `.hide_edge`, and `.hide_face`.
In the longer term, this design can significantly simplify
and improve code, as described in T95965.
Branch: `refactor-mesh-hide-generic`