refactor: routes.component.js and creation of ToastMaster

[HowardBraham]

Description

This PR is part of the larger effort to add React.lazy to routes.

I would be very surprised if I did not break functionality somewhere, as this was a large and tough refactor. It needs some good QA, and Harika has been doing some testing that has passed.

Summary of what I did:

• Pulled all Toast-related logic out of routes.component.js and into the new ToastMaster
• Pulled everything else I could pull out into routes-helpers.js
• Moved things out of the general selectors.js and actions.ts into toast-master-selectors.ts
• Simplification of some Pointless Thunks™

For later PRs:

• Convert routes.component.js to TypeScript
• Convert routes.component.js to Hooks
• Convert routes.component.js to react-router v6
• Eliminate routes.container.js

Related issues

Progresses: MetaMask/MetaMask-planning#2898

Manual testing steps

Test all the Routes and all the Toasts

Screenshots/Recordings

Before

After

Pre-merge author checklist

• [x] I've followed MetaMask Contributor Docs and MetaMask Extension Coding Standards.
• [x] I've completed the PR template to the best of my ability
• [x] I’ve included tests if applicable
• [x] I’ve documented my code using JSDoc format if applicable
• [x] I’ve applied the right labels on the PR (see labeling guidelines). Not required for external contributors.

Pre-merge reviewer checklist

• [ ] I've manually tested the PR (e.g. pull and build branch, run the app, test code being changed).
• [ ] I confirm that this PR addresses all acceptance criteria described in the ticket it closes and includes the necessary testing evidence such as recordings and or screenshots.