Keep "Use Wallet" on the contract page

[treeder]

It's a bit jarring to click "Use Wallet" from a contract address page and be taken to the the wallet asking for the private key. If we could keep the interactions directly on the contract page, it would feel quite a bit nicer. So maybe a button to enable the "write" functions which are grayed out and disabled by default. Asks for private key, then enables those functions.