[PIP-9] Introduce Wrapped Bitcoin Jars

A proposal by the Pickle Core Devs.

We have recently seen increasing interest from the community for BTC-based PickleJars. See the following forum post for a more in-depth discussion on this topic: https://forum.pickle.finance/t/wrapped-bitcoin-pickle-jar/60/15

The Pickle Finance team considers that adding BTC-based PickleJars would be advantageous as:

1. it would bring in additional revenue to those staking PICKLE tokens and to the Treasury (per the recently passed PIP-8: https://signal.pickle.finance/#/pickle/proposal/QmY9brRECFQ61y7JTVQHktDMCseXUiC2NaMcYMEAbkLHbo); and
2. it aligns with our broader goal of stabilizing synthetic assets (stablecoins being just one example of a synthetic asset).

If this proposal is passed, PickleJars with the following strategies will be added:

1. the ETH/wBTC Jar which farms UNI and re-invests them to earn more ETH/wBTC LP tokens; and
2. the crvRenWBTC Jar which farms CRV and re-invests them to earn more crvRenWBTC tokens.

At this time, the allocation of the PICKLE farming rewards will remain unchanged, meaning that these BTC-based PickleJars will not immediately be entitled to PICKLE rewards. However, we invite the community to propose changes in the allocation of PICKLE rewards in light of these new Jars if this proposal passes.