Proposal: Adding a Plasma Login Manager

[David Edmundson]

>
> I'd lean towards merging them in one repo. Neither are useful on their own, are they?

Only benefit is the ability to change the backend in the future
without a messy git history.

> Then it probably makes sense to move the repo(s) to the plasma namespace.

Yeah, will do once we know where we want them.

> I'm a bit confused about "I also aim to incubate it into the KDE ecosystem to have full autonomy over the project and merging stuck patches.".

What I was trying to say  was that we should host the backend part we
need, and maybe cherry-pick some pending PRs from SDDM.
I want to leave upstream SDDM alone so I don't actively break things
others might be using.

David