Blender Git Loki

Fix T81997: Subsurf Optimal Display sticks after object conversion

When using Optimal Display, some edges are not flagged `ME_EDGEDRAW` |
`ME_EDGERENDER`.
When the modifier is applied through the UI in the modifier stack this is
not an issue because the `modifyMesh` callback is run with
`MOD_APPLY_TO_BASE_MESH` (this will effectively turn of Optimal
Display).
When converting to mesh though, this will just get an evaluated mesh
(where the edge flags are still the same as with the subdivision
modifier).
Now ensure every edge is flagged to draw after conversion.

Maniphest Tasks: T81997

Differential Revision: https://developer.blender.org/D9331