Truncate the row cells to a maximum size
As the purpose of this backend is to serve 100 rows of every dataset split to moonlanding, to show them inside a table, we can optimize a bit for that purpose.

In particular, when the 100 rows are really big, the browsers have a hard time rendering the table, in particular Safari. Also: this can generate a lot of traffic, just to show a table that nobody will inspect in detail.

So: the proposal here is to limit the size of every cell returned in the `/rows` endpoint. The size can be specified as the number of bytes of the generated JSON. We will also add a flag to tell if a cell has been truncated.

To keep it simple, we will make it mandatory, but a further version might make it optional through a URL parameter or another endpoint.

- [ ] check if it fixes https://github.com/huggingface/datasets-preview-backend/issues/177
Truncate the row cells to a maximum size: As the purpose of this backend is to serve 100 rows of every dataset split to moonlanding, to show them inside a table, we can optimize a bit for that purpose.

In particular, when the 100 rows are really big, the browsers have a hard time rendering the table, in particular Safari. Also: this can generate a lot of traffic, just to show a table that nobody will inspect in detail.

So: the proposal here is to limit the size of every cell returned in the `/rows` endpoint. The size can be specified as the number of bytes of the generated JSON. We will also add a flag to tell if a cell has been truncated.

To keep it simple, we will make it mandatory, but a further version might make it optional through a URL parameter or another endpoint.

- [ ] check if it fixes https://github.com/huggingface/datasets-preview-backend/issues/177