Implement Proxy Account for Teams Pallet

[dharjeezy]

We want to be able to set up proxy for teams, It just means that an account is being set up as a proxy like admin account to oversee it. The use case is that in a business someone might leave the company, and someone else might take over, but they would both require an admin to do the reassignment and cleanup.

The conversation is that we can either do this or both:

1. Include a param in the extrinsic for creating team, the param will be the proxy account Id.

2. Expose an extrinsic for accepting the proxy for a team.

• We also need to implement a StorageMap for storing the team hash as key with the proxy account id as the value.