Check kind of type in Python (#909)

Moves the kind of type detection from the query for reflection from
EdgeQL to Python because the computed property use in the query turned
out to be too costly:
```
─────────────────────────── Query ───────────────────────────
analyze
with
    module schema
select ➊  Type {
    ➋  kind := assert_exists(
        'Object' IF Type IS ObjectType ELSE
        ➌  'Scalar' IF Type IS ScalarType ELSE
        ➍  'Array' IF Type IS Array ELSE
        'NamedTuple' IF ➎  Type[IS Tuple].named ?? false ELSE
        ➏  'Tuple' IF Type IS Tuple ELSE
        ➐  'Range' IF Type IS Range ELSE
        ➑  'MultiRange' IF Type IS MultiRange ELSE
        ➒  'Pseudo' IF Type IS PseudoType ELSE
        <str>{},
        message := "unexpected type",
    ),
};

────────────────────────────────────────────── Coarse-grained Query Plan ──────────────────────────────────────────────
     │    Time        Cost  Loops   Rows  Width │ Relations
root │  2282.4   837696.69    1.0  248.0     32 │ schema::ArrayExprAlias, schema::Tuple, schema::ScalarType,
     │                                          │ schema::Range, schema::RangeExprAlias, schema::MultiRange,
     │                                          │ schema::TupleExprAlias, schema::PseudoType, schema::ObjectType,
     │                                          │ schema::MultiRangeExprAlias, schema::Array
```

vs
```
──────────────────────── Query ────────────────────────
analyze
with
    module schema
select ➊  Type {
    ➋  is_object := Type IS ObjectType,
    ➌  is_scalar := Type IS ScalarType,
    ➍  is_array := Type IS Array,
    ➎  is_named_tuple := Type[IS Tuple].named ?? false,
    ➏  is_tuple := Type IS Tuple,
    ➐  is_range := Type IS Range,
    ➑  is_multi_range := Type IS MultiRange,
    ➒  is_pseudo := Type IS PseudoType,
};

────────────────────────────────────────────── Coarse-grained Query Plan ──────────────────────────────────────────────
     │   Time     Cost  Loops   Rows  Width │ Relations
root │  210.6  6316.56    1.0  248.0     32 │ schema::ArrayExprAlias, schema::Tuple, schema::ScalarType, schema::Range,
     │                                      │ schema::RangeExprAlias, schema::MultiRange, schema::TupleExprAlias,
     │                                      │ schema::PseudoType, schema::ObjectType, schema::MultiRangeExprAlias,
     │                                      │ schema::Array
```