feat(): migrate to monorepo, add bullmq integration

[kamilmysliwiec]

PR Checklist

Please check if your PR fulfills the following requirements:

• The commit message follows our guidelines: https://github.com/nestjs/nest/blob/master/CONTRIBUTING.md
• Tests for the changes have been added (for bug fixes / features)
• Docs have been added / updated (for bug fixes / features)

PR Type

What kind of change does this PR introduce?

• Bugfix
• Feature
• Code style update (formatting, local variables)
• Refactoring (no functional changes, no api changes)
• Build related changes
• CI related changes
• Other... Please describe:

What is the new behavior?

• Yarn workspaces (for managing multiple packages and their deps in one repository)
• Lerna (for versioning & publishing packages and auto-generating changelog)
• TypeScript project references (for sharing common code between packages)
• Added bullmq integration (@nestjs/bullmq)

Does this PR introduce a breaking change?

• Yes
• No

Other information