Instrument PyPI and Composer events via Snowplow

What does this MR do?

This MR adds instrumentation for the PyPI and Composer repositories so that we can measure usage and adoption in our SiSense dashboard.

PyPI

• Instrumented events for publishing, downloading and listing python packages

Composer

• Composer does not behave like other traditional package managers. You aren't uploading a package, so much as you are registering the location of a package.json file somewhere in git. So, I only tracked one event and called it register_package

Closes #214905 (closed)

Screenshots

Does this MR meet the acceptance criteria?

Conformity

• Changelog entry
• Documentation (if required)
• Code review guidelines
• Merge request performance guidelines
• Style guides
• Database guides
• Separation of EE specific content

Availability and Testing

• Review and add/update tests for this feature/bug. Consider all test levels. See the Test Planning Process.
• Tested in all supported browsers
• Informed Infrastructure department of a default or new setting change, if applicable per definition of done

Security

If this MR contains changes to processing or storing of credentials or tokens, authorization and authentication methods and other items described in the security review guidelines:

• Label as security and @ mention @gitlab-com/gl-security/appsec
• The MR includes necessary changes to maintain consistency between UI, API, email, or other methods
• Security reports checked/validated by a reviewer from the AppSec team