Allow ternary operator in filter expressions

[SH-Exact]

This PR introduces the support of the ternary operator in filter expressions. The operator's name is CASE and works with IF, THEN, ELSE.

wServices.article.some({
  where: {
    unit: {
	  EQ: {
	    CASE: {
		  IF: <filterExpression>,
		  THEN: <value>,
		  ELSE: <value>
	    }	  
	  }
    }
  }
})

Nested ternary operators are also possible

wServices.article.some({
  where: {
    unit: {
	  EQ: {
        CASE: {
          IF: <filterExpression>,
          THEN: <value>,
          ELSE: {
            CASE: {
              IF: <filterExpression>,
              THEN: <value>,
              ELSE: <value>
            }
          }
        }	  
	  }
    }
  }
})

[OlivierCosti]

Getting a type error here: