Implement staking contract without delegation

[dbcfd]

Context: The library named LibStaking defines the staking behavior, while the contract responsible for handling the staking logic is the SubnetActor (SubnetActorDiamond.sol).

TBD: Describe here or in the resulting PR the changes introduced at each layer to accomplish our implementation.

Note: If the word collateral is encountered, it is safe to assume it refers to the stake amount in a subnet.

[JulissaDantes]

We need to update this ticket to implement the staking contract, including delegation, or create a separate ticket to update the staking contract with delegation (I prefer the latter). CC: @carsonfarmer.

[carsonfarmer]

It looks like the ticket already contains a mention of this: recallnet/ipc#145 (comment). So perhaps it is just a matter of creating a sub-ticket and linking it to the original issue as part of the "task" list? Feel free to just do that 👍.