Potential malformed output when using `CARQUET_REPETITION_OPTIONAL`

[jerome-fmad]

Reproduction steps:

1. Build the latest master at time of writing (a303659) with examples and tests.
2. Run build/example_nullable /tmp/example_nullable.parquet.
3. Install the DuckDB CLI (https://duckdb.org/install/?platform=linux&environment=cli)
4. Run the DuckDB CLI and use SELECT * FROM '/tmp/example_nullable.parquet';

Expected output: an ASCII representation of the table contents.

Actual output:

D SELECT * FROM '/tmp/example_nullable.parquet';
Invalid Error:
TProtocolException: Invalid data

---

Another hand-made example:

#include <assert.h>

#include <carquet/carquet.h>

int main(int argc, char* argv[]) {
        carquet_error_t err = CARQUET_ERROR_INIT;
        carquet_schema_t* schema = carquet_schema_create(&err);
        carquet_schema_add_column(schema, "nullable", CARQUET_PHYSICAL_INT32, NULL, CARQUET_REPETITION_OPTIONAL, 0, 0);
        int32_t col_idx = carquet_schema_find_column(schema, "nullable");

        carquet_writer_options_t opts;
        carquet_writer_options_init(&opts);

        carquet_writer_t* writer = carquet_writer_create("/tmp/repro.parquet", schema, &opts, &err);
        int32_t value = 1337;
        carquet_writer_write_batch(writer, col_idx, (const void*)&value, 1, NULL, NULL);

        carquet_status_t status = carquet_writer_close(writer);
        assert(status == CARQUET_OK);

        return 0;
}

Results in the DuckDB CLI saying the following:

D SELECT * FROM '/tmp/repro.parquet';
Invalid Error:
Out of buffer

---

This isn't so much a bug report as a "request for comment", since I acknowledge the possibility that DuckDB is in the wrong here.