Deprecate 3-arg FunctionClass constructor (#18472)

Also, make two new constructors no longer experimental.

Followup to #16849

Author: nicolasstucki

library/src/scala/quoted/Quotes.scala

@@ -4318,16 +4318,14 @@ trait Quotes { self: runtime.QuoteUnpickler & runtime.QuoteMatching =>
       *   -  ...
       *   -  Nth element is `FunctionN`
       */
-      // TODO: deprecate in 3.4 and stabilize FunctionClass(Int)/FunctionClass(Int,Boolean)
-      // @deprecated("Use overload of `FunctionClass` with 1 or 2 arguments","3.4")
+      @deprecated("Use overload of `FunctionClass` with 1 or 2 arguments","3.4")
       def FunctionClass(arity: Int, isImplicit: Boolean = false, isErased: Boolean = false): Symbol
 
       /** Class symbol of a function class `scala.FunctionN`.
        *
        *  @param arity the arity of the function where `0 <= arity`
        *  @return class symbol of `scala.FunctionN` where `N == arity`
        */
-      @experimental
       def FunctionClass(arity: Int): Symbol
 
       /** Class symbol of a context function class `scala.FunctionN` or `scala.ContextFunctionN`.
@@ -4336,7 +4334,6 @@ trait Quotes { self: runtime.QuoteUnpickler & runtime.QuoteMatching =>
        *  @param isContextual if it is a `scala.ContextFunctionN`
        *  @return class symbol of `scala.FunctionN` or `scala.ContextFunctionN` where `N == arity`
        */
-      @experimental
       def FunctionClass(arity: Int, isContextual: Boolean): Symbol
 
       /** The `scala.PolyFunction` built-in trait. */

project/MiMaFilters.scala

@@ -6,6 +6,7 @@ object MiMaFilters {
     // New API in 3.4.X
     ProblemFilters.exclude[ReversedMissingMethodProblem]("scala.quoted.Quotes#reflectModule.ValOrDefDefTypeTest"),
     ProblemFilters.exclude[ReversedMissingMethodProblem]("scala.quoted.Quotes#reflectModule.ValOrDefDefMethods"),
+    ProblemFilters.exclude[ReversedMissingMethodProblem]("scala.quoted.Quotes#reflectModule#defnModule.FunctionClass")
     // New API in 3.4.X
   )
   val TastyCore: Seq[ProblemFilter] = Seq(

tests/run-tasty-inspector/stdlibExperimentalDefinitions.scala

@@ -68,8 +68,6 @@ val experimentalDefinitionInLibrary = Set(
   "scala.annotation.init$.region",
 
    //// New APIs: Quotes
-  // Should be stabilized in 3.4.0
-  "scala.quoted.Quotes.reflectModule.defnModule.FunctionClass",
   "scala.quoted.Quotes.reflectModule.FlagsModule.AbsOverride",
   // Can be stabilized in 3.4.0 (unsure) or later
   "scala.quoted.Quotes.reflectModule.CompilationInfoModule.XmacroSettings",