[feature]: allow setting to_self_delay with OpenChannel

[AndySchroder]

We have the max-cltv-expiry option for lnd (

lnd/sample-lnd.conf

Line 448 in 6377f98

; max-cltv-expiry=2016

) which I believe sets the to_self_delay value for the channel. This seems to be a global value for all channels that are opened. As the fee markets get more competitive, we may need more time to get closing transactions confirmed cheaply. We shouldn't have to restart lnd to change this. Also, we may want to set the time_lock_delta to higher values on certain channels and on those channels we will need an even higher to_self_delay value than normal channels to work properly.

An example of a channel that has a higher time_lock_delta value from a normal channel is if that channel is used for long term HOLD invoices. We may want to offer longer time_lock_delta values to allow routing payments for invoices that define a high cltv_expiry but charge a higher fee on those channels for agreeing to lock up funds for a longer period of time.

Once lightning/bolts#1117 gets complete, would also like the ability to update to_self_delay with UpdateChannelPolicy since we can update time_lock_delta with UpdateChannelPolicy.

[AndySchroder]

Also, please add time_lock_delta. I realize this is a policy that can be update with UpdateChannelPolicy, but OpenChannel now allows setting fee_rate and base_fee. It make sense to be able to set all channel policies when opening a channel and not having to quickly update them after opening (and potentially already announcing).

[AndySchroder]

Also, it looks like there are some new options inbound_base_fee_msat and inbound_fee_rate_ppm in UpdateChannelPolicy. I think these come from #6703 . They should probably be added too if they are not already.