add init tip distribution account functionality in between epochs

[segfaultdoc]

Problem

We want initialize a validator's TipDistributionAccount (TDA) in between epochs.

Summary of Changes

Upon startup a validator initializes the TipManager object, which in turn creates an in memory TDA. There is no tx propagated to the network initializing it with the program until the validator is leader. Each slot the validator is a leader for, it'll check to see if it should init the TDA on-chain.

The logic is as follows:

1. Receive packets in bundle_stage
2. Check to see if need to init a TDA. Need to init if the epoch has changed OR the currently set TDA does not exist in the bank. The latter would imply an init-tda tx was never propagated or accepted by the network.
3. If need to init submit as a bundle top of block along with a maybe_init_config tx (existing code).
4. Check to see if the on-chain tip_receiver == my_tda, if not then submit a tx to the network as TOB or 2nd of Block to change tip-receiver to the validator's current epoch TDA

[whistlinwilly]

sorry for delay ser

[buffalu]

initial review. main points:

• i don't think we need tip manager to be locked?
• do we need to store mutable state in tip_manager? i think we can get away without it.
• nits

[buffalu]

few smaller comments, most of it seems gucci mane