Function diskless_span_extension 

pub fn diskless_span_extension(
    current_start: u64,
    current_len: u64,
    next_start: u64,
    next_len: u64,
    same_object: bool,
    max_bytes: u64,
) -> Option<u64>

Extend an object byte span only across a contiguous whole indexed range.

The span extends exactly when the next range sits in the same object, starts where the span ends, and the grown span stays within max_bytes.