JIT: Transform floating SELECT(a < b, a, b) to NativeMin(a, b)

[BoyBaykiller]

Example:

static float Min(float a, float b)
{
    return a < b ? a : b;
}

;; ------ BASE
G_M000_IG02: 
       vucomiss xmm1, xmm0
       jbe      SHORT G_M000_IG04
 
G_M000_IG03:
       ret      
 
G_M000_IG04:
       vmovaps  xmm0, xmm1
 
G_M000_IG05: 
       ret      

;; ------ DIFF
G_M21498_IG02: 
       vminss   xmm0, xmm0, xmm1

G_M21498_IG03:
       ret      

Handles all these cases. I compared the codegen of every single one against it to be sure its correct:
https://godbolt.org/z/389jvnfW4

Fix #116802

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[Copilot]

Pull request overview

This PR extends CoreCLR JIT if-conversion select optimization to recognize floating-point conditional selects that compute min/max (e.g., a < b ? a : b) and replace them with a native SIMD min/max node on xarch, enabling codegen like vminss/vmaxss instead of compare + branch.

Changes:

• Allow GT_STORE_LCL_VAR / GT_RETURN if-conversion when the value type is floating-point (in addition to integral/I).
• Add TrySelectToMinMax to rewrite eligible floating GT_SELECT nodes into gtNewSimdMinMaxNativeNode (xarch).
• Add an early bailout to avoid producing floating-point GT_SELECT nodes unless they optimize to a non-SELECT form.

[BoyBaykiller]

we call gtNewConditionalNode before which counts as change

[BoyBaykiller]

@MihuBot -nuget