chore: adding e2e for signature decoding api

[jpuri]

Description

adding e2e for signature decoding api

Related issues

Fixes: https://github.com/MetaMask/MetaMask-planning/issues/3625

Manual testing steps

NA

Screenshots/Recordings

NA

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.

[github-actions]

CLA Signature Action: All authors have signed the CLA. You may need to manually re-run the blocking PR check if it doesn't pass in a few minutes.

[jpuri]

The PR can not be merged till the env variable are enabled for main build in develop branch.