This will allow users to manage channels in a bulk

*Nice to have for future versions:

• Color for each group/tag
• Switch channel groups based on routing/liquidity events

Features/rules added with this:

• LNDg default settings works like the "parent default" settings
• When adding channel A from LNDg group to a new group G, channel A is removed from group LNDg
• When adding the same channel A to a new group H, A will belong to group G and H simultaneously
• When removing channel A from group H and G, A will return to LNDg

1. Groups can be partially configurable:
   1.1. It's allowed to create a group for AR and another for AF
   1.2. It's allowed to split AR or AF into further more groups with the condition of: channel A cannot be in group G and H if both groups have a single setting in common. Say: G->AR-Time:5 and H->AR-Time:2 (except Enabled settings)
   1.3. In contrast to 1.2 if you add some channels to a rebalancer group G but do NOT assign any rebalance settings to it, the rebalancer will act as if none of these channels were assigned to the newly created group and will get AR settings from LNDg instead. (The rebalance would get triggered with the LNDg default settings)
   1.4. GUI/LND settings and AR-Workers are owned by LNDg group. (can be changed in the future)

Summary: Any group settings can be split into multiple groups if and only if channels within those same groups doesnt share any common setting