Remove wallet_enable

[rekmarks]

wallet_enable should be removed. We can add something like it back later if we think it's a good idea.

Original Issue Content

wallet_enable is designed to be a one-stop shop for dapp developers. It lets you:

• Request arbitrary permissions
  • Including eth_accounts, which gets its own property on the result object.
• Install / update snaps

Currently, it can partially succeed/fail, which is why the result object includes an errors property:

https://github.com/MetaMask/snaps-monorepo/blob/15212ab511e22f7b85c3c032a96fdf40f54dc12d/packages/rpc-methods/src/permitted/enable.ts#L24-L29

This method is something of an abominable mishmash. We should consider whether it should exist at all.