Description

This PR adds a feature flag to be used during the development of the non-EVM initiative. To use the flag during development just change the value of the flag to true and access it using process.env.BTC_BETA_SUPPORT.

Related issues

Fixes: https://github.com/MetaMask/accounts-planning/issues/466

Manual testing steps

No manual testing required

Screenshots/Recordings

Not applicable

Pre-merge author checklist

• I've followed MetaMask Contributor Docs and MetaMask Extension Coding Standards.
• I've completed the PR template to the best of my ability
• I’ve included tests if applicable
• I’ve documented my code using JSDoc format if applicable
• 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.