use a heuristic to determine whether or not to use asynchronous publishing

[wjwwood]

See: #183 (comment)

The proposal from the linked pull request would be, use synchronous publishing:

• if the reliability is BEST_EFFORT (type bounded or unbounded)
• if the reliability is RELIABLE and the type is bounded and the maximum size is less than MAX_SYNC_PAYLOAD

Where MAX_SYNC_PAYLOAD is some maximum size that can be used without asynchronous publishing.

Use asynchronous publishing:

• if the reliability is RELIABLE and the type is bounded and the maximum size is more than MAX_SYNC_PAYLOAD
• if the reliability is RELIABLE and the type is unbounded (has no maximum size)

Something else to consider is whether or not messages with unbounded size can always be published with synchronous publishing, even with reliability as BEST_EFFORT.

[clalancette]

Closing, since with Foxy now being End-of-Life, this repository is no longer used.