Allow for 0 reserve in channels

[benthecarman]

I dont think this will let the user have 0 reserve but it will at least give them slightly more inbound from the LSP not having any reserve

[TonyGiorgio]

Is 0 an allowed value? I think above dust is still required.

[benthecarman]

it says

If the calculated proportional value is less than 1000 sats, it will be treated as 1000 sats instead, which is a safe implementation-specific lower bound

So this will enforce that it doesn't error with dust