feat: plugin subscribe subinfo flags

[kenkalang]

Proposed Changes

• Allow plugin subscribe via direct_plugin_exports to pass SubInfo (e.g. #{rap => true})
• Adds direct_plugin_exports_test_subinfo integration test

Types of Changes

What types of changes does your code introduce to this project?
Put an x in the boxes that apply

• Bugfix (non-breaking change which fixes issue #XXXX)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to not work as expected)
• Documentation (correction or otherwise)
• Cosmetics (whitespace, styles...)
• DevOps (Build scripts, pipelines...)