Drop 9.2

[michaelpj]

Per our new deprecation policy, since the current binding constraint is GHCup recommended, which is on 9.4.

I did my usual "evaluate away the CPP" trick, I haven't attempted to simplify what's left. I do wonder if we're close to not needing hie-compat at all?

[wz1000]

I have pushed a fairly aggressive cleanup of session loader stuff which is more likely than not broken in some horribly subtle ways. Let's see what CI says.

[jhrcek]

I did my best to remove the rest of dead code, configs and fix few warnings 😃

I found one more opportunity to simplify things here:

haskell-language-server/ghcide/src/Development/IDE/GHC/Compat/Plugins.hs

Lines 86 to 91 in 287ee42

	-- | Plugins aren't stored in ModSummary anymore since GHC 9.2, but this
	-- function still returns it for compatibility with 8.10
	initPlugins :: HscEnv -> ModSummary -> IO (ModSummary, HscEnv)
	initPlugins session modSummary = do
	session1 <- initializePlugins (hscSetFlags (ms_hspp_opts modSummary) session)
	return (modSummary{ms_hspp_opts = hsc_dflags session1}, session1)

Though I'm missing some ghc domain knowledge to be able to act on it.
@wz1000 @michaelpj feel free to do something about it or leave it as is.
Otherwise LGTM as is.

[konn]

LGTM as for Splice Plugin, thanks!

[soulomoon]

LGTM!

[wz1000]

Let's not squash all of these changes before merging, in particular I would like to keep 7665e2c as a separate commit in the history so that it is easy to view these changes in isolation or possibly revert.

[michaelpj]

Great work team.

[michaelpj]

Let's land this, it seems to work and we can do more cleanup as we want.

[michaelpj]

Let's not squash all of these changes before merging

I hit "rebase and merge", so it's all in there.