V2 Cover unit tests: createStakingPool & performStakeBurn

[roxdanila]

createStakingPool

• should create new pool
• Should allow anyone to call this method
• Should deploy and initialize a new minimal beacon proxy StakingPool contract
• Should emit the StakingPoolCreated event
• Should increment the stakingPoolCount

performStakeBurn

• should perform a burn a cover with 1 segment and 1 pool allocation
• Should allow only internal contracts to call it
• Should update totalActiveCoverInAsset if tracking is enabled
• Should call burnStake on the staking contract
• Should update allocation cover amount in NXM - amountPaidOut?