Use CompileFast() instead of Compile() in ExpressionFactoryUtilities

[illyaz]

Description

Replace LambdaExpression.Compile() with CompileFast() from FastExpressionCompiler in ExpressionFactoryUtilities

Why This is Needed

CreatePropertyWriter compiles property accessor expressions on every converter registration. With Remora.Discord registering a large number of converters at startup, the cumulative cost is significant and regresses further on .NET 10.

Benchmark results (source):

BenchmarkDotNet v0.15.8, Windows 11 (10.0.26200.7840/25H2/2025Update/HudsonValley2)
Intel Core i9-14900K 3.20GHz, 1 CPU, 32 logical and 24 physical cores                                                                                                                                      
.NET SDK 10.0.103                                                                                                                                                                                          
  [Host]    : .NET 10.0.3 (10.0.3, 10.0.326.7603), X64 RyuJIT x86-64-v3                                                                                                                                    
  .NET 10.0 : .NET 10.0.3 (10.0.3, 10.0.326.7603), X64 RyuJIT x86-64-v3                                                                                                                                    
  .NET 9.0  : .NET 9.0.13 (9.0.13, 9.0.1326.6317), X64 RyuJIT x86-64-v3                                                                                                                                    
                                                                                                                                                                                                           

| Method       | Job       | Runtime   | Mean         | Error     | StdDev    | Ratio  | RatioSD |
|------------- |---------- |---------- |-------------:|----------:|----------:|-------:|--------:|
| Original     | .NET 10.0 | .NET 10.0 | 1,415.535 us | 7.8831 us | 6.5828 us | 402.69 |    8.05 |                                                                                                         
| FastCompiler | .NET 10.0 | .NET 10.0 |     3.517 us | 0.0534 us | 0.0712 us |   1.00 |    0.03 |
|              |           |           |              |           |           |        |         |
| Original     | .NET 9.0  | .NET 9.0  |   290.462 us | 3.4586 us | 3.2351 us |  72.12 |    1.55 |
| FastCompiler | .NET 9.0  | .NET 9.0  |     4.029 us | 0.0786 us | 0.0772 us |   1.00 |    0.03 |

Alternatives Considered

Additional Details

• FastExpressionCompiler works directly on standard System.Linq.Expressions
• No public API changes whatsoever
• Happy to submit a PR if you're open to the dependency