Add weekly automated CEF updater workflow & update to 148.0.7778.180

[Xenius97]

Summary

Added a GitHub Actions workflow that automatically updates CEF every Tuesday at 08:00 CET.
After updating, the workflow automatically creates a pull request containing the changes, allowing maintainers to review and merge it manually.

This makes keeping CEF up-to-date significantly more streamlined and removes the need for manual update handling (except for review and merge).

Motivation

Updating CEF manually is repetitive and easy to forget.
By automating the process with a scheduled workflow and automatic PR creation, updates can be delivered faster and more consistently while still preserving manual review before merging.

Before using it, make sure to verify that secrets.GITHUB_TOKEN is configured correctly and working properly (it is already used by another workflow).

Checklist

• Your code should follow the coding guidelines.
• Smaller pull requests are easier to review. If your pull request is beefy, your pull request should be reviewable commit-by-commit.