Ensure the distinction between MetaMetrics and a provider are clearer. cc @coreyjanssen

Related to MetaMask/metamask-extension#16711

Onboarding Screen with Copy

!

Screenshot 2022-11-30 at 12.24.48 PM.png

Technical Details
[ ] Add new copy of text
[ ] Add link to allow the user to Add Custom Network and switch to network for new wallet creation

Acceptance Criteria

• Translations are not required for this feature but should go out in next release
• New users have the option to change the RPC URL during opt-in
• New & existing users have the option to change the RPC URL of default networks (cannot delete)
• Existing users token detection and other related data still populates as expected
• Transactions, Swaps, Send, Approve
• Custom RPC for mainnet edit the RPC after wallet creation and confirm you are not seeing duplicate networks
• Test light/dark mode network input boxes not visible