Protect internals of the provider classes using hash names

Currently in `snaps-monorepo` we wrap the Ethereum provider in a `Proxy`, to prevent access to internal fields. A better alternative would be to protect these fields in the first place using hash names, which are not accessible in any way.

Start by locating the provider classes in the TypeScript repository and reading how snaps-monorepo currently wraps the Ethereum provider in a Proxy. Identify the internal fields that require protection and review the provider tests, if present. Done means those internals are protected directly and the Proxy workaround is no longer needed.

Written by the indexing model from the issue text.