fixes #3546

This PR introduces a new MultilinePromptLogger that allows the status of multiple in-progress threads to be reported and viewed during a Mill evaluation:

MultilinePromptLogger is basically a minimal translation of the current ticker API to work with a multi-line prompt. There's probably a lot of other interesting improvements we can make now that we are multi-line, but this is a decent start that lets people know what their parallel build is doing. The UI works correctly both during scrolling and not-scrolling, and uses the same minimal ANSI codes that the existing ticker uses, so hopefully we won't hit any more edge cases that we aren't already hitting today

From an implementation perspective, MultilinePromptLogger is mostly a drop in replacement for the old PrintLogger, except:

1. It prints multiple ticker lines at vertically at the bottom of the terminal, and has the logs printed above

2. It requires that you use .endTicker() after every .ticker("...") call, so we can know where we should clear the ticker status (previously they always just got overriden by the next .ticker call)

3. We need to introduce a withPaused{...} block so that when you're running REPLs and stuff the prompt is not shown

4. The logger needs to extend AutoCloseable, since it uses a background thread to keep the prompt UI up to date

5. We only can support logs which end with newlines. This means things like interactive progress bars and other ANSI magic won't work in the scrollback. This is a limitation of the current implementation that is hard to fix without going for more advanced techniques, but should be enough for the vast majority of logs and is a similar limitation as a lot of other tools.

6. Ticker max width is hardcoded to <120 characters wide, with longer ticker strings being shortened in the middle. This width is arbitrary but should hopefully work for most projects, and we can figure out how to make it configurable or dynamic in a follow up

7. I experimented with having the ticker logic live in the Mill client rather than server, which would make more sense, but we need the server to have the ability to enable/disable the ticker logic to run console and similar interactive tasks, and so it has to live in the server

The old ticker remains available at --disable-prompt. Further improvements can come after 0.12.0.