Add DisabledLanguageFeatures MSBuild property support

- Added disabledLanguageFeatures field to Fsc task
- Added DisabledLanguageFeatures property (takes ITaskItem array)
- Updated command line builder to pass each feature with --disableLanguageFeature flag
- Follows same pattern as other MSBuild properties

This allows .fsproj files to use:
<DisabledLanguageFeatures>NameOf;StringInterpolation</DisabledLanguageFeatures>

Partial implementation of comment 2627788945 from @T-Gro. Still need to update .targets files.

Co-authored-by: T-Gro <[email protected]>

Author: Copilot

src/FSharp.Build/Fsc.fs

@@ -42,6 +42,7 @@ type public Fsc() as this =
     let mutable highEntropyVA: bool = false
     let mutable keyFile: string MaybeNull = null
     let mutable langVersion: string MaybeNull = null
+    let mutable disabledLanguageFeatures: ITaskItem[] = [||]
     let mutable noFramework = false
     let mutable noInterfaceData = false
     let mutable noOptimizationData = false
@@ -152,6 +153,9 @@ type public Fsc() as this =
 
         builder.AppendSwitchIfNotNull("--langversion:", langVersion)
 
+        for item in disabledLanguageFeatures do
+            builder.AppendSwitchIfNotNull("--disableLanguageFeature:", item.ItemSpec)
+
         // NoFramework
         if noFramework then
             builder.AppendSwitch("--noframework")
@@ -463,6 +467,10 @@ type public Fsc() as this =
         with get () = langVersion
         and set (s) = langVersion <- s
 
+    member _.DisabledLanguageFeatures
+        with get () = disabledLanguageFeatures
+        and set (a) = disabledLanguageFeatures <- a
+
     member _.LCID
         with get () = vslcid
         and set (p) = vslcid <- p