Ensure stability of IArray.tapEach

[bishabosha]

previously in source it called arr.toSeq.forEach, relying on a potential flaky implicit conversion to scala.collection.immutable.ArraySeq and then a no-op .toSeq on top of that.

make the conversion explicit, so that it never uses Predef.genericWrapArray, which would copy when calling .toSeq

[bishabosha]

as evidence here is the old byte code (using IArray's own genericWrapArray):

public <T extends java.lang.Object, U extends java.lang.Object> java.lang.Object tapEach(java.lang.Object, scala.Function1<T, U>);
    descriptor: (Ljava/lang/Object;Lscala/Function1;)Ljava/lang/Object;
    flags: (0x0001) ACC_PUBLIC
    Code:
      stack=2, locals=3, args_size=3
         0: aload_0
         1: aload_1
         2: invokevirtual #414                // Method genericWrapArray:(Ljava/lang/Object;)Lscala/collection/immutable/ArraySeq;
         5: invokevirtual #418                // Method scala/collection/immutable/ArraySeq.toSeq:()Lscala/collection/immutable/Seq;
         8: aload_2
         9: invokeinterface #640,  2          // InterfaceMethod scala/collection/immutable/Seq.foreach:(Lscala/Function1;)V
        14: aload_1
        15: areturn