20.7
```
SELECT indexOf(['a', 'b', 'c'], toLowCardinality('a'))

┌─indexOf(['a', 'b', 'c'], toLowCardinality('a'))─┐
│                                               1 │
└─────────────────────────────────────────────────┘
```

20.8
```
SELECT indexOf(['a', 'b', 'c'], toLowCardinality('a'))


Received exception from server (version 20.8.3):
Code: 43. DB::Exception: Received from localhost:9000. DB::Exception: Types of array and 2nd argument of function "indexOf" must be identical up to nullability, cardinality, numeric types, or Enum and numeric type. Passed: Array(String) and LowCardinality(String).. 
```

https://github.com/ClickHouse/ClickHouse/pull/12550

/cc @myrrc 

const ColumnString::Chars & data, const ColumnArray::Offsets & offsets,
        const ColumnString::Offsets & string_offsets, const ColumnString::Chars & item_values,
        Offset item_offsets, PaddedPODArray<ResultType> & result,
        const NullMap * data_map, const NullMap * item_map)
    {
        invokeCheckNullMaps<true>(data, offsets, string_offsets, item_values, item_offsets, result, data_map, item_map);
    }
    static inline void process(
        const ColumnString::Chars & data, const ColumnArray::Offsets & offsets,
        const ColumnString::Offsets & string_offsets, const ColumnString::Chars & item_values,
        const ColumnString::Offsets & item_offsets, PaddedPODArray<ResultType> & result,
        const NullMap * data_map, const NullMap * item_map)
    {
        invokeCheckNullMaps<false>(data, offsets, string_offsets, item_values, item_offsets, result, data_map, item_map);
    }
};
}
template <class ConcreteAction, class Name>
class FunctionArrayIndex : public IFunction
{
public:
    static constexpr auto name = Name::name;
    static FunctionPtr create(const Context &) { return std::make_shared<FunctionArrayIndex>(); }
    
    String getName() const override { return name; }
    bool useDefaultImplementationForNulls() const override { return false; }
    bool useDefaultImplementationForLowCardinalityColumns() const override { return false; }