Now it support only `String` and `FixedString`

https://github.com/ClickHouse/ClickHouse/blob/33aefa832b3c544934a757cc9d0e284252a1dd3e/src/Storages/MergeTree/MergeTreeIndexFullText.cpp#L809

Seems that `LowCardinality(String)` can be supported too, because we only use `column->getDataAt` to retrieve data and it will work on `LowCardinality(String)` in same way as for `String`
https://github.com/ClickHouse/ClickHouse/blob/33aefa832b3c544934a757cc9d0e284252a1dd3e/src/Storages/MergeTree/MergeTreeIndexFullText.cpp#L543
https://github.com/ClickHouse/ClickHouse/blob/33aefa832b3c544934a757cc9d0e284252a1dd3e/src/Storages/MergeTree/MergeTreeIndexFullText.cpp#L145
{
    if (version != 1)
        throw Exception(ErrorCodes::LOGICAL_ERROR, "Unknown index version {}.", version);
    for (auto & bloom_filter : bloom_filters)
    {
        istr.read(reinterpret_cast<char *>(
                bloom_filter.getFilter().data()), params.filter_size);
    }
    has_elems = true;
}
MergeTreeIndexAggregatorFullText::MergeTreeIndexAggregatorFullText(
    const Names & index_columns_,
    const String & index_name_,
    const BloomFilterParameters & params_,
    TokenExtractorPtr token_extractor_)
    : index_columns(index_columns_)
    , index_name (index_name_)
    , params(params_)
    , token_extractor(token_extractor_)
    , granule(
        std::make_shared<MergeTreeIndexGranuleFullText>(
            index_name, index_columns.size(), params))
{
}
MergeTreeIndexGranulePtr MergeTreeIndexAggregatorFullText::getGranuleAndReset()