Support for 'in' and 'contains' operators

[piotrszul]

For empty collections and comparable primitive and literal types.

'in' operator should return empty when left argument is empty - Collections exclusions

Details

Expected: null but got: false ==> expected: <null> but was: <false>

• ups in coll [If the left-hand side of the operator is the empty collection is empty, the result is empty]
• ups in emptycoll [empty in empty is empty]

'contains' operator should return empty when right argument is empty - Collections exclusions

Details

Expected: null but got: false ==> expected: <null> but was: <false>

• coll contains empty [null]
• coll contains ups [reverse of: If the left-hand side of the operator is the empty collection is empty, the result is empty]
• emptycoll contains ups [empty in empty is empty]