Create operating fund

[whoabuddy]

This PR adds the operating fund contract

• fixes Create operating fund for timed vault contracts #57

This also modifies the treasury to interact solely with the operating fund, creating an extra layer of protection and allowing us to open up core proposals sooner than originally anticipated in #39

Left to do:

• treasury: set withdrawal amount up to 2% of its own balance (or just 2% flat?)
• op fund: add code and logic to interact with deployed timed vaults
• op fund: allow for regular transfer/movement as well? L2 treasury 😆

Notable Changes:

• treasury: maps and constants added to track a 4,320 BTC block period for withdrawals (30 days)
• treasury: one withdrawal per period is allowed, separate one for STX, one for FT (DAO token)
• treasury: read-only functions added: get-current-period, get-stx-claim and get-ft-claim
• treasury: read-only function added: get-contract-info with constants and config
• treasury: private functions added: update-stx-claim, update-ft-claim with write-once logic
• treasury: withdrawal can happen once per period, no way to recover missed/past periods (activity-based)

[whoabuddy]

So with other contracts we have a pattern of STX, sBTC, and DAO token. In the treasury we have STX, FT, and NFT in a more broad definition.

If we track the claims per period for just FT, then we could only withdraw sBTC or DAO token once per period, no separation.

I think if we focus on the treasury as being the secure place for the DAO token, STX, and sBTC then we can scope it better then just being a general treasury.

The question becomes what if another FT or NFTs get added? Do we need to support that now or introduce something later?

To sum it up in a different way, should we streamline it so that:

• treasury designed for STX, sBTC, and DAO token only
• treasury 30day withdrawals allowed to operating fund at (or up to?) 2% of balance
• operating fund can be tapped for up to 20% of its balance by a timed vault
• operating fund supports withdraw for STX and any FT on allow list (DAO/sBTC by default)
• drop NFT support for now, can address with separate extension later (and core proposal)