feat: add GossipsubMaxIHaveLength config

[mkermani144]

Description

In the comments here:

js-libp2p-gossipsub/src/constants.ts

Lines 199 to 203 in 9e57215

	* peer within a heartbeat, to protect from IHAVE floods. You should adjust this value from the
	* default if your system is pushing more than 5000 messages in GossipsubHistoryGossip heartbeats;
	* with the defaults this is 1666 messages/s.
	*/
	export const GossipsubMaxIHaveLength = 5000

It is stated that it should be configured if needed:

You should adjust this value from the default if your system is pushing more than 5000 messages in GossipsubHistoryGossip heartbeats

But it's not configurable. constants.GossipsubMaxIHaveLength is used all over the code.

Expected behaviour

I think it should either be a config, or the comment should be updated. As a side note, based on my investigations, this is not part of the spec anyways.

[wemeetagain]

Happy to accept a PR for this feature