Propertly Truncate Paired Single Move Instructions

[Geotale]

Matches hardware in rounding paired singles after move operations!!
Move operations consist of operations which only transfer direct bits (including absolute values and merges)
This also accounts for ps_rsqrte because it has a similar quirk
Specifically in hardware they're rounded in accordance to their slot:

• PS0 rounds only the mantissa in accordance to the set rounding mode
• PS1 truncates the mantissa

ps_rsqrte also only truncates for PS0 for some reason ^^;
This has all been tested on hardware, along with a few edge case tests to ensure this implementation works

[Dentomologist]

Can you add a unit test matching the tests you ran on hardware? That would help show what has been tested and prevent any future regressions.

Also, the second commit should be squashed into the first one.

[Geotale]

I can probably commit to the hwtests repo if I can figure out how to get it set up ^^;
I also will definitely squash the commits but I am not confident that I won't have to change things and I'd rather not have to multiple times if possible :D

[Dentomologist]

While it would definitely be good to have that in the hwtests repo, I was primarily thinking about here which gets run on every PR.

[Geotale]

I'm mildly afraid to try that bc this is interpreter-only and would require an entire thing somehow setting that up :,D

[JosJuice]

I would very much like a hwtest. And if we have that, I don't think there's any need to require a unit test on top. Yes, being able to automatically test stuff is nice, but:

1. This code doesn't get changed often at all, so running the relevant hwtests manually is a surmountable task, and
2. The time it would take to set up a bunch of unit tests for the interpreter would probably be better spent getting hwtests to run automatically like we run FifoCI, or setting up some other kind of testing system that can run both on console and on Dolphin. Unit tests are inherently less useful than hwtests because we can't run them on hardware.

[Tilka]

I've confirmed with your hwtest (dolphin-emu/hwtests#56) plus isync that the ps_merge*/ps_mr/ps_neg/ps_abs/ps_nabs changes match hardware. If you move the changes for those opcodes (and the shared code) into a separate PR, we can get that merged now and leave ps_sel/ps_rsqrte/ps_sum0/ps_sum1 verification for later.

[Geotale]

Oh right I forgot about sum0 and sum1, ty for reminding me ^^ -- I was planning try to figure out what in the world is failing the 3 specific tests with ps_rsqrte first though :O

[Tilka]

Based on some limited testing, I think ps_sel doesn't have the NaN/infinity special case.