Automated selection of validators

[saumyakaran]

GOAL: To return the "best" set of 16 validators for a nominator to stake on based on their budget (stake amount)

Taking stake amount as input:

• [ ] Determine all possible combinations of 16 validators
• [ ] Run offline phragmen to determine probable stake allocation for each possible combination of 16 validators to stake on
• [ ] Accordingly return the highest rewarding set of validators for the nominator to stake on

Future iterations: Improve the list by taking into account risk levels and probability of the validator being selected in the next era.

Helpful resources:

• Min-norm max-flow Problem - https://research.web3.foundation/en/latest/polkadot/NPoS/2.%20The%20min-norm%20max-flow%20problem.html#-2.-the-min-norm-max-flow-problem--mnmf-

• Sequential Phragmen - https://wiki.polkadot.network/docs/en/learn-phragmen