Specialize primitiveAt based on format

[PalumboN]

Here is the code used for the experiment of compiling specialized versions of the primitiveAt.

• I created a subclass DRSpecialPrimitiveCompilerCompiler with the magic
• It looks for the format number to specialize
  https://github.com/PalumboN/opensmalltalk-vm/blob/503cb52076a8bda5ef88a8eb8862004accd80135/smalltalksrc/VMMaker/InterpreterPrimitives.class.st#L978-L987
• And adds a special case to interpret the format as a constant directly.