[mono] Reenable some amd64 intrinsic tests, enable amd64 ISA extensions when AOTing...

[mono] Reenable some amd64 intrinsic tests, enable amd64 ISA extensions when AOTing, several intrinsics fixes (#53752)

Changes:

* Consolidate SSE shuffle constant unrolling

  Remove `OP_SSE2_SHUFFLE`, which is unused.

  Rename `OP_SSE_SHUFFLE` to `OP_SSE_SHUFPS`, to make this more consistent with
  the naming convention used for other SSE shuffles.

  Use `immediate_unroll_*` instead of hand-writing branch emission. These
  branch tables are huge (in the simplest case, with 256 different constant
  values, we can spend over 1KB of code on nothing but `shufps` and `jmp`s, and
  the cost gets worse if any tail duplication happens), and are currently
  emitted inline.  Future work ought to:

  1. use a sequence of extractelement/insertelement instructions, which can be
  optimized into a constant shuffle when the shuffle control parameter is
  constant, and otherwise generates a high-latency but low-code-size fallback
  (note that this only works for shuffles); or

  2. emit the fallback branch tables out of line and use `llvm.is.constant` to
  generate either a constant shuffle or a call to a fallback shuffle branch
  table function (the cost isn't too bad: a direct-call/ret pair would add ~4-5
  cycles and eat an RSB slot on top of the cost of the branch table).

  Fixes `JIT/HardwareIntrinsics/X86/Regression/GitHub_21855/GitHub_21855_r`.

* Fix intrinsification for MathF.Round

  `OP_SSE41_ROUNDS` takes two source registers, not one.

  TODO: Investigate what happens with `llvm.round` and
  `llvm.experimental.constrained.round`.

  Fixes `JIT/Intrinsics/MathRoundSingle_r`,
  `JIT/Math/Functions/Functions_r`, and
  `JIT/Performance/CodeQuality/Math/Functions/Functions`.

* Clean up intrinsic group lookup

  Use a dummy never-supported intrinsic group as a default fallback, instead of
  adding a special-case "intrinsic group not present" branch

  Correctly intrinsify get_IsSupported even when not using LLVM

  Fixes spurious `System.PlatformNotSupportedException`s when calling
  `get_IsSupported` when the LLVM backend isn't being used.

* The "not" SSE comparions are unordered, so use the appropriate unordered LLVM
  IR comparisons

  Add labeled constants for the immediate parameter we pass to CMPSS/CMPSD.

  Fixes `Regressions.coreclr/GitHub_34094/Test34094`.

* Fix `LoadAndDuplicateToVector128`

  `LoadAndDuplicateToVector128` should load exactly one 8-byte value from memory
  before broadcasting it into both lanes in a 128-bit result vector.

  Fixes `JIT/HardwareIntrinsics/X86/Sse3/LoadAndDuplicateToVector128_r`.

* Implement constant unrolling for `Sse41.DotProduct`

  As with shuffles, the fallback jump table should probably be kept out of line
  someday; `vdpps` uses 6 bytes of space, so any fallback jump table for the
  selection control mask will be at least 1.5kb large.

  Fixes `JIT/HardwareIntrinsics/X86/Sse41/DotProduct_r`.

* Implement constant unrolling for `Sse41.Blend`

  The usual: big jump blobs should be out of line, possible to use
  extract/insertelement.

* Zero is part of the domain of `lzcnt` and shouldn't yield an undef.

  Use fully-defined `llvm.ctlz` when implementing `OP_LZCNT32/64`.

  Fixes `JIT/HardwareIntrinsics/X86/Regression/GitHub_21666/GitHub_21666_r`

* Unify amd64/arm64 vector extraction handling

  Removes `OP_EXTRACT_U1` and `OP_EXTRACT_U2`. Instead, sign/zero extension is
  determined via `inst_c1` for `OP_EXTRACT_*` and `OP_XEXTRACT_*` (and
  `OP_EXTRACTX_U2`, which doesn't seem to be generated as part of intrinsic
  translation), which must be set to a MonoTypeEnum.

  Replaces `OP_EXTRACT_VAR_*` with `OP_XEXTRACT_*`.

  Fixes `JIT/Regression/JitBlue/GitHub_23159/GitHub_23159` and
  `JIT/Regression/JitBlue/GitHub_13568/GitHub_13568`.

* Remove `OP_DPPS`; it is unused

* Disable `JIT/Regression/CLR-x86-JIT/V1.1-M1-Beta1/b143840` when running with mono LLVM AOT

* Disable finalizearray when running with mono LLVM AOT

* Disable Vector256_1/Vector128_1 tests on wasm

* Enable sse4.2, popcnt, lzcnt, bmi, and bmi2 when AOT compiling the runtime
  tests.

* Pass the runtime variant to `helixpublishwitharcade.proj`, and forward this
  runtime variant to testenvironment.proj.

  This is used to selectively enable LLVM JIT on the LLVM AOT lanes. Removes
  the hack added to CLRTest.Execute.Bash.targets that did this for arm64 (which
  happens to only have an LLVM AOT lane for runtime tests right now).

* Enable `JIT/HardwareIntrinsics/General/Vector128_1/**`,
  `JIT/HardwareIntrinsics/General/Vector256/**`,
  `JIT/HardwareIntrinsics/General/Vector256_1/**`, and
  `JIT/HardwareIntrinsics/X86/General/IsSupported*/**` for LLVM AOT on amd64.