[TAKE TWO] Next revision of increasing nomination pool limits & commission

NOTE: This was originally #39

Nomination pool usage is increasing, and nomination pool commission has now rolled out on Polkadot. This referendum changes the following nomination pool settings to account for this:

• maxPools from 256 -> 512 (currently at 131 pools)
• maxMembers from 16,384 -> 49,152 (currently at >12,000 members)
• globalMaxCommission from 0% -> 10%, enabling pool commission on Polkadot.

Further reading:

• Polkadot Forum: https://forum.polkadot.network/t/next-revision-of-increasing-nomination-pool-limits/2498/5
• GitHub tracking issue: https://github.com/paritytech/substrate/issues/14321