Add `reverseBV` to clash prelude

[rowanG077]

Slow in simulation implementation:

-- | Reverse bitvector
reverseBV :: KnownNat n => BitVector n -> BitVector n
reverseBV = v2bv . reverse . bv2v

Originally mentioned by @christiaanb in #2694 (comment)

1. add this function to clash-prelude and
2. make something with better time complexity such as https://graphics.stanford.edu/~seander/bithacks.html#ReverseParallel

Originally posted by @DigitalBrains1 in #2694 (comment)

Hah I had noted this too, but didn't comment on it. I think I didn't even write it down for myself, which was dumb. Anyway...... the current implementation is fine in hardware, and a quick implementation would probably need a primitive. Unless you use clashSimulation from Clash.Magic to use the quick implementation in simulation but use v2bv . reverse . bv2v when generating HDL. That will write your primitive for you (but like a usual primitive, it's still up to you to make sure simulation and HDL match in behaviour).

[edit]
The quick implementation should probably deconstruct the bitvector and construct it again at the end because logical operations on bitvector are needlessly expensive for this application, in this PR I achieved a roughly threefold speedup of logical operations that way.
[/edit]

[edit 2]
I read this wrong: I read this as that Rowan was going to do the implementation. Once the issue is raised, I'll copy-paste the essence of the above to that issue.
[/edit 2]

[rowanG077]

Once implemented remove reverseBV from:

clash-compiler/clash-cores/src/Clash/Cores/Crc/Internal.hs

Lines 118 to 120 in e6522d7

	-- | Reverse bitvector
	reverseBV :: KnownNat n => BitVector n -> BitVector n
	reverseBV = v2bv . reverse . bv2v

[jvnknvlgl]

Chiming in here to mention that I'm using the same function here in Clash.Cores.Sgmii.Common:

clash-compiler/clash-cores/src/Clash/Cores/Sgmii/Common.hs

Lines 80 to 82 in 0b7f4c1

	-- | Reverse the bits of a 'BitVector'
	reverseBV :: (KnownNat n) => BitVector n -> BitVector n
	reverseBV = v2bv . reverse . bv2v

So if something new is added this has to be replaced as well.