XQuery: Refine parameter types to arguments types of function call

[ChristianGruen]

declare %basex:inline(0) function local:type($value) {
  if($value instance of xs:integer) then 'int' else 'string'
};
local:type('x')

…can be optimized to…

declare %basex:inline(0) function local:type($value) { 'string' };
local:type("x")