Liquidity Threshold in Config File for all Peers

Currently, [documentation](https://docs.lightning.engineering/lightning-network-tools/loop/autoloop#liquidity-thresholds) shows that liquidity thresholds for autoloop (--incoming-threshold & --outgoing-threshold) can only be set per channel ID or peer pubkey. This means you can't keep your LiT node running and have autoloop properly balancing all channels. It would be very helpful to be able to set thresholds for all peers for my node in my configuration file, for example:

> loop.autoloop=true
> loop.type=in
> loop.incomingthreshold=.40
> loop.outgoingthreshold=.40

I imagine it would be helpful for many users of autoloop/LiT as well.

Read the linked autoloop liquidity-threshold documentation first, then trace how --incoming-threshold and --outgoing-threshold are parsed and how per-channel or peer values are applied. Done means the configuration-file thresholds in the example apply to all peers while preserving existing per-channel and per-peer behavior.

Written by the indexing model from the issue text.