[Chore] Improve morley compilation time

Description

Improve compilation time on morley. Part 1 definitely improves things. Part 2, I'm not exactly convinced by. In my initial investigation, it seemed to save quite a bit of time (around 25-30 seconds), but after tweaking Part 1 it's pretty close to the margin of error. UPD: after some more testing, the cost is around 10 seconds for morley on my machine. Which doesn't seem like much, but little things like this tend to add up. OTOH, if we don't care about this, I would suggest getting rid of DeMorganScope by putting constraints on parts of the type into the superclass of ForbidT. This will cost us around another 10 seconds (as measured on my machine).

Some concrete numbers from CI:

• Before !1341 (merged): 6:16
• After !1341 (merged): up to 10:06, but more realistically 8:19
• This MR: 6:15

Related issue(s)

Resolves None. I could create an issue, but that seems kinda pointless.

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