Make NodeManager optional

[benthecarman]

Was able to fix #1071 while i was at it

This puts the node manager in a RwLock that is by default off, only until create_node_manager is called will we have a lightning node and on-chain wallet. Otherwise it will use fedimint when there is no nodemanager or throw an error if neither are configured.

[benthecarman]

This is getting close, want to write tests for everything but in my manual testing things seem to be working well

[benthecarman]

~note to self: need to make sure bringing back a node manager doesn't create a new node and instead brings back the old nodes~

[TonyGiorgio]

needs rebase

[TonyGiorgio]

Errors when receiving on chain when only a federation is added

[benthecarman]

Went through full testing guide, everything is working as of now. Going to add a few more things to it that will now apply with this

[benthecarman]

discussed in meeting: don't default remove empty node managers