This commit switches the bufferpool to use the zeropool implementation
for sync pools.

The stdlib sync.Pool implementation has an issue where it causes an
additional heap allocation per Put() call when used with byte slices.

github.com/colega/zeropool package has been specifically designed to
work around this issue, which reduces GC pressure and improves
performance.

This also fixes the bufferpool's pkg benchmark to use a new pool per
test, to avoid other tests influencing the behavior of the benchmark and
sets it to report the allocations.

This fixes the Message's Reset() call to allow reuse of the first
segment.

Prior to this fix, the first segment was discarded after the first Reset
call, effectively causing a new segment to be initialized on every Reset
call.

By reusing the first segment, the number of heap allocations is reduced
and therefore performance is increased in use cases where the message
object is reused.

The fix involved associtating the segment to the message and fixing
checks to ensure the data of the segment is re-allocated after the
reset.

A benchmark is included to show the current performance of this.

Momentarily, while refactoring is going on.

This shows that the BenchmarkUnmarshal_Reuse is broken.

The prior version isn't commented and it's hard to reason about.

This makes the captable release more efficient, avoid unnecessary
allocations.

This avoids some duffcopy calls and improves perf.

The TextField is a reference to a specific text field inside a struct.
It records both the pointer and value locations inside a struct, which
may be used to fetch or update the underlying value.