Reserve memory for FOH in-range

[EgorBo]

This should allow jit to use relocs (mainly, for boxed statics), e.g.:

static DateTime Date { get; set; }

Codegen for getter (same for setter):
Previously (after #77737):

; Assembly listing for method get_Date()
       48B8901762B29D020000 mov      rax, 0x29DB2621790
       488B00               mov      rax, qword ptr [rax]
       C3                   ret
; Total bytes of code 14

New codegen:

; Assembly listing for method get_Date()
       488B0571E41000       mov      rax, qword ptr [(reloc 0x7fff54fc17b8)]
       C3                   ret
; Total bytes of code 8

jit-diff (-f --pmi --cctors):

Summary of Code Size diffs:
(Lower is better)

Total bytes of base: 58930581
Total bytes of diff: 58879402
Total bytes of delta: -51179 (-0.09 % of base)
Total relative delta: -378.96
    diff is an improvement.
    relative diff is an improvement.


Total byte diff includes 206 bytes from reconciling methods
        Base had    0 unique methods,        0 unique bytes
        Diff had    2 unique methods,      206 unique bytes

Top file regressions (bytes):
         164 : Microsoft.CodeAnalysis.dasm (0.01% of base)

Top file improvements (bytes):
      -46542 : Microsoft.Diagnostics.Tracing.TraceEvent.dasm (-1.28% of base)
        -834 : Newtonsoft.Json.dasm (-0.09% of base)
        -729 : System.Private.Xml.dasm (-0.02% of base)
        -708 : System.Reflection.DispatchProxy.dasm (-3.03% of base)
        -311 : System.Data.Common.dasm (-0.02% of base)
        -306 : Microsoft.Extensions.DependencyInjection.dasm (-0.49% of base)
        -297 : System.Data.OleDb.dasm (-0.09% of base)
        -294 : System.Private.CoreLib.dasm (-0.02% of base)
        -240 : FSharp.Core.dasm (-0.01% of base)
        -192 : System.Composition.Hosting.dasm (-0.22% of base)
        -102 : System.Composition.TypedParts.dasm (-0.19% of base)
         -90 : System.Linq.Expressions.dasm (-0.01% of base)
         -84 : System.Threading.RateLimiting.dasm (-0.05% of base)
         -54 : OSExtensions.dasm (-0.52% of base)
         -48 : System.ComponentModel.TypeConverter.dasm (-0.02% of base)
         -48 : System.Security.Cryptography.dasm (-0.01% of base)
         -40 : System.Speech.dasm (-0.01% of base)
         -36 : System.Net.Sockets.dasm (-0.02% of base)
         -30 : System.Console.dasm (-0.05% of base)
         -30 : Microsoft.CodeAnalysis.CSharp.dasm (-0.00% of base)
         -30 : System.Runtime.Caching.dasm (-0.05% of base)
         -30 : System.Transactions.Local.dasm (-0.01% of base)
         -24 : Microsoft.Extensions.DependencyInjection.Abstractions.dasm (-0.09% of base)
         -24 : Microsoft.Extensions.FileProviders.Physical.dasm (-0.14% of base)
         -24 : System.Diagnostics.EventLog.dasm (-0.02% of base)

4929 total methods with Code Size differences (4921 improved, 8 regressed), 355176 unchanged.

Not sure it's guaranteed to return 8-bytes aligned memory though.