Adds a property, `hookNames`, to each RPC method handler export in `app/scripts/lib/rpc-method-middleware` and a function, `selectHooks`, to select from them.
`createMethodMiddleware` receives a giant `opts` object that includes a bunch of different methods from `MetaMaskController` and its subcontrollers. Each method implementation only requires a subset of these methods to do its work. Because they need some kind of name, we call these methods "hooks". With this change, whenever an RPC method is called, `selectHooks` will be called to ensure that each method only receives the hooks that it needs in order to do its job.
This implementation is based on [work in `snaps-skunkworks`](https://github.com/MetaMask/snaps-skunkworks/blob/a3e1248/packages/rpc-methods/src/utils.ts#L17-L34) that will be merged in the near future.
We're bumping from `^6` to `^8`. All imports are now named, and they have been updated. This is a breaking change, in that support for `eth_signTransaction` is added in `^8.0.0`. We do not support this method in our UI, so our middleware stack has been instrumented to reject.
In addition, there are some non-breaking behavioral changes in this version that reviewers should be aware of, see the [7.0.0 release](https://github.com/MetaMask/eth-json-rpc-middleware/releases).
