Revert "[.NET] Remove EFS update on reloading assemblies" but with deferred call

It turns out this call was needed after all, it ensures new scripts are included
in the global class list by updating EFS for them. In my previous PR I must've
only tested scripts that have been opened or loaded by the editor at some point
so I didn't encounter the bug.

This reverts the previous PR but with a deferred call to avoid reintroducing
the bug that the PR fixed. Updating EFS here is still too early, so we defer
the call to ensure the type info is available.