hg-core: remove the `Operation` trait...
hg-core: remove the `Operation` trait
There is no way to currently define a trait which can both return references
to `self` and to passed data, which is what we would need.
Generic Associated Types may fix this and allow us to have a unified interface.
See: rust
#44265
Differential Revision:
https://phab.mercurial-scm.org/D8862