Expose PartialEq for ChannelMonitor

[benthecarman]

Closes #1912

This would be the simplest way to accomplish this I believe, another idea could be use would be to use Ord and have it compare something like current_holder_commitment_number to see which is newer.

[wpaulino]

As is, this is missing some fields that need to be compared and were not included here. If we decide to expose this, we should also add a test so that we don't miss any fields added later on.

Alternatively, we could just expose a helper to determine whether two ChannelMonitors are for the same channel through their channel_keys_id. These must be unique as they are used in the key derivation per channel.

[benthecarman]

As is, this is missing some fields that need to be compared and were not included here. If we decide to expose this, we should also add a test so that we don't miss any fields added later on.

Can do

Alternatively, we could just expose a helper to determine whether two ChannelMonitors are for the same channel through their channel_keys_id. These must be unique as they are used in the key derivation per channel.

I would like to use this to test that my storage is working correctly, doing this wouldn't really give guarantees that we are persisting things correctly

[TheBlueMatt]

If we want to remove the manual implementation, we probably can - we'll have to derive PartialEq/Eq for Events (which we should probably do generally anyway) and we'll have to move the Sign object out somehow. We could swap ChannelMonitorImpl for (Signer, ChannelMonitorImpl) or split it into two structs.

[benthecarman]

Just gonna close this for now, thought it'd be a simple couple line change.