Move `develop` to `testnet` network

[lachlanglen]

Currently, alpha.potlock.org (deployed develop branch) utilizes NEAR mainnet network. However, this is not practical for testing and it should use testnet network.

Here are PotLock contract addresses for testnet:

1. Registry: registry.potlock.testnet
2. Donation: donate.potlock.testnet
3. PotFactory: potfactory.potlock.testnet

Plus NEAR Social contract: v1.social08.testnet

Steps to complete:

• When utilizing wallet selector, choose network (testnet or mainnet) based on environment. develop environment should use testnet network.
• 6-8 dummy projects will need to be created on testnet (and NEAR social details added) to fill out Projects page
• New pots will need to be deployed from the testnet PotFactory contract (address above)
• Any components that use NEAR Social will need to use the testnet contract address ("v1.social08.testnet")
• Backend will need to populate testnet data (there is none currently - no projects, no donations - so that simplifies it)
• Probably will need to separate backend deployments by env to use appropriate network in indexing/db service