chore(shard-distributor): introduce LoadBalancingMode dynamic property

[arzonus]

What changed?

• Introduced dynamic property for LoadBalancingMode
• Merged MigrationConfig and Config to DynamicConfig
• Split StaticConfig and DynamicConfig into 2 different files
• Renamed ConfigMode to MigrationMode
• Removed non-used ShardManager* dynamic properties
• LoadBalancingMode has been added

Why?

• LoadBalancingMode dynamic property is going to be used to set a load balancing mode for shard rebalancing, and will be needed in the next PR.

How did you test it?

• Unit test
• Run canary locally