[clarity] sBTC-DB.clar | Port Over sBTC-registry.clar

[setzeus]

As detailed in sister issues #3970 , #3958, & #3957, there is a clear need for a state-persistent contract that should keep track of some items from sBTC asset boot contract & some items from the previous StackerDB setup (please click into linked issues for more details on either requirement).

This issue is made for the Clarity working group to create a new sBTC-DB.clar contract not unsimilar to the sBTC-registry.clar contract found in sBTC-mini.

A few requirements of the data required includes:

sBTC (only .sBTC can write):

• Pending peg-in requests
• Pending peg-out requests
• Hand-offs
• Is-DKG-stale

StackerDB (only a boot contract, maybe .pox-4 can write):

• tuples of {signer: principal, slots: uint}

[setzeus]

Going to keep two separate contracts for storage, one for stackerDB & one for sBTC.

[setzeus]

Latest update here: https://github.com/stacks-network/stacks-blockchain/tree/add-storage-contracts