Line dependent buffer

[pdet]

In this PR, we modify the buffer size to be dependent on the max_line_size option.

This ensures that our buffers are always appropriately sized when max_line_size is set correctly, allowing us to read CSV files with very large lines.

Summary:

By default:

• max_line_size: 2097152 bytes (~2MB)
• buffer_size: 16 * max_line_size (~32MB)
• per_thread_bytes: 4 * max_line_size (~8MB)

The buffer_size and per_thread_bytes will only be adjusted if max_line_size is set to a value larger than the default.

[Mytherin]

Thanks for the PR! LGTM - only the serialization is broken by this PR. Perhaps we can delete the old setting and add in a new one instead of changing the type?

[Mytherin]

Thanks! One more minor comment

[Mytherin]

Thanks!