Split OpCode.hs and add module for opcode parameters

Due to TemplateHaskell stage restrictions, we can't define parameters
in the same module as we're using them for TH, so we have to define
all module parameters in a separate module.

This patch therefore splits OpCodes.hs in two, adding that module and
moves most code there (types, parameters, etc.). The remaining parts
in OpCodes.hs, the actual opcode definitions, now use more parameters
instead of direct field definitions (more will come later)

Signed-off-by: Iustin Pop <iustin@google.com>
Reviewed-by: Adeodato Simo <dato@google.com>