Reduce minimum required balance in Lockup

[telezhnaya]

https://github.com/near/core-contracts/tree/master/lockup#early-vesting-termination
The last 2 paragraphs there say:

The amount withdrawn in the event of termination by Contract Creator may be lower than the initial contract amount. It's because the contract has to maintain the minimum required balance to cover storage of the contract code and contract state. The amount of NEAR tokens locked to maintain the minimum storage balance is 35 NEAR. 35 NEAR is enough to cover storage for 350000 bytes on Mainnet at the price of 1 NEAR per 10000 bytes.

If there is still a termination balance deficit due to the minimum required balance, the owner may decide to fund the deficit on this account to finish the termination process. This can be done through a regular transfer action from an account with a liquid balance.

We need to:

• storage prices become 10 times smaller, we should change 35 NEAR to 3.5 NEAR
• add to Lockup Factory the step with the transfer to lockups additional NEAR to cover these operations (TBD: all lockups? at the moment of creation? at the moment of termination? how to understand, should we transfer 35 or 3.5? Account could be created at any time with old code version)

[telezhnaya]

@AngelBlock @yessins let's decide whether we want to implement a second task here