Replace use of .size with .length for Arrays

Invoking .size on arrays is valid, but requires an implicit conversion to SeqLike. This incurs a compile time overhead and more importantly a runtime overhead, as the Array must be wrapped before the method can be invoked. For example, the difference in generated byte code is:

  public int withSize();
    Code:
       0: getstatic     #23                 // Field scala/Predef$.MODULE$:Lscala/Predef$;
       3: aload_0
       4: invokevirtual #25                 // Method array:()[I
       7: invokevirtual #29                 // Method scala/Predef$.intArrayOps:([I)Lscala/collection/mutable/ArrayOps;
      10: invokeinterface #34,  1           // InterfaceMethod scala/collection/mutable/ArrayOps.size:()I
      15: ireturn

  public int withLength();
    Code:
       0: aload_0
       1: invokevirtual #25                 // Method array:()[I
       4: arraylength
       5: ireturn

Author: sksamuel <sam@sksamuel.com>

Closes #5376 from sksamuel/master and squashes the following commits:

77ec261 [sksamuel] Replace use of .size with .length for Arrays.