Redundant write barriers around byref-like structs

[EgorBo]

Reported in #111127 (comment) by @NinoFloris

public class Program
{
    object _obj = new();

    Test M0() => new Test() { Obj = _obj, Obj1 = _obj, Obj2 = _obj };

    void M1(ref Test ret) => ret = new Test() { Obj = _obj, Obj1 = _obj, Obj2 = _obj };

    void M2(out Test ret) => ret = new Test() { Obj = _obj, Obj1 = _obj, Obj2 = _obj };

    public ref struct Test
    {
        public object Obj;
        public object Obj1;
        public object Obj2;
    }
}

Currently all three M0, M1, M2 emit redundant write barriers, although, they're not needed due to "ByRefLike" modifier on Test struct (meaning it can live only on stack):

; Assembly listing for method Program:M0():Program+Test:this (FullOpts)
G_M000_IG01:
       push     rsi
       push     rbx
       mov      rbx, rdx
G_M000_IG02:
       mov      rsi, gword ptr [rcx+0x08]
       mov      rdx, rsi
       mov      rcx, rbx
       call     CORINFO_HELP_CHECKED_ASSIGN_REF
       lea      rcx, bword ptr [rbx+0x08]
       mov      rdx, rsi
       call     CORINFO_HELP_CHECKED_ASSIGN_REF
       lea      rcx, bword ptr [rbx+0x10]
       mov      rdx, rsi
       call     CORINFO_HELP_CHECKED_ASSIGN_REF
       mov      rax, rbx
G_M000_IG03:
       pop      rbx
       pop      rsi
       ret      
; Total bytes of code 50


; Assembly listing for method Program:M1(byref):this (FullOpts)
G_M000_IG01:
       push     rsi
       push     rbx
       mov      rbx, rdx
G_M000_IG02:
       mov      rsi, gword ptr [rcx+0x08]
       mov      rdx, rsi
       mov      rcx, rbx
       call     CORINFO_HELP_CHECKED_ASSIGN_REF
       lea      rcx, bword ptr [rbx+0x08]
       mov      rdx, rsi
       call     CORINFO_HELP_CHECKED_ASSIGN_REF
       lea      rcx, bword ptr [rbx+0x10]
       mov      rdx, rsi
       call     CORINFO_HELP_CHECKED_ASSIGN_REF
       nop      
G_M000_IG03:
       pop      rbx
       pop      rsi
       ret      
; Total bytes of code 48


; Assembly listing for method Program:M2(byref):this (FullOpts)
G_M000_IG01:
       push     rsi
       push     rbx
       mov      rbx, rdx
G_M000_IG02:
       mov      rsi, gword ptr [rcx+0x08]
       mov      rdx, rsi
       mov      rcx, rbx
       call     CORINFO_HELP_CHECKED_ASSIGN_REF
       lea      rcx, bword ptr [rbx+0x08]
       mov      rdx, rsi
       call     CORINFO_HELP_CHECKED_ASSIGN_REF
       lea      rcx, bword ptr [rbx+0x10]
       mov      rdx, rsi
       call     CORINFO_HELP_CHECKED_ASSIGN_REF
       nop      
G_M000_IG03:
       pop      rbx
       pop      rsi
       ret      
; Total bytes of code 48

Expected:

no CORINFO_HELP_CHECKED_ASSIGN_REF calls in the codegen.

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