Add builtin functions for unary and binary Wasm operators

[SpaceManiac]

Operations:

• integer types
  • clz count leading zeroes
  • ctz count trailing zeroes
  • popcnt population count
  • rotl and rotr bitwise rotation
• floating-point types
  • abs absolute value
  • ceil ceiling
  • floor floor
  • trunc
  • nearest
  • sqrt
  • min minimum (two args)
  • max maximum (two args)
  • copysign (two args)

Syntax possibilities:

• Method: foo.count_leading_zeroes()
• Global: count_leading_zeroes(foo)

Or maybe we should adopt a uniform function call syntax that makes the difference not matter?