Add mage target for serve dev webui tool

[kschiffer]

Summary

This PR adds the serve dev webui tool as a mage target, so that it can also be run via tools/bin/mage dev:serveDevWebui.

Changes

• Rename the tool from serve-dev-stack (clashing with existing mage target) to serve-dev-webui
• Add a new mage target dev:serveDevWebui to the Dev module

Notes for Reviewers

Since this tool should become the unified go-to way of running the stack for frontend development, it should also have an appropriate mage target.

Checklist

• Scope: The referenced issue is addressed, there are no unrelated changes.
• Compatibility: The changes are backwards compatible with existing API, storage, configuration and CLI, according to the compatibility commitments in README.md for the chosen target branch.
• Documentation: Relevant documentation is added or updated.
• Testing: The steps/process to test this feature are clearly explained including testing for regressions.
• Infrastructure: If infrastructural changes (e.g., new RPC, configuration) are needed, a separate issue is created in the infrastructural repositories.
• Changelog: Significant features, behavior changes, deprecations and fixes are added to CHANGELOG.md.
• Commits: Commit messages follow guidelines in CONTRIBUTING.md, there are no fixup commits left.