Refactor @metamask/providers and make it use #hashFunctions for private methods

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This is a proposal to do refactoring of the `@metamask/providers` `StreamProvider` and make its private methods and properties use `#hash` approach if possible. That way it would not be exposing methods and properties within its prototype chain which can be a security concern.

It is discovered that `harden` function from [Secure EcmaScript](https://www.npmjs.com/package/ses) which is used in Snaps and LavaMoat, is freezing some parts of the stream which makes it impossible to work. Because of that, a special way of using Proxy was introduced. By having a real private methods and properties it might be easier to secure this type of issues in the future.

Start by locating the @metamask/providers StreamProvider implementation and reviewing how its private methods and properties are exposed through the prototype chain. Read the issue’s context about SES harden, Snaps, LavaMoat, and the Proxy workaround. Done means determining whether # private methods and properties can replace the current approach without breaking stream behavior or security.

Written by the indexing model from the issue text.