Consider screen view ID from the screen view context (close #14)

[matus-tomlein]

Description

This PR addresses issue #14 to consider the screen ID in the screen context entity, not just the one in the screen view event.
This is important to be able to attribute events other than the screen view event to the screen view (it's mainly necessary to enable screen engagement tracking).

Updates to integration tests

Unfortunately, the integration test data seems to be buggy as the ID in the screen context entity does not reflect the screen view events – all events have the same ID 4e8c2289-b1cd-4915-90de-2d87e1976a58.
After making this change and considering that ID, the test results changed slightly – there is a higher number of views per session as all non-screen view events have the extra 4e8c2289-b1cd-4915-90de-2d87e1976a58 ID.

I think we would need to collect new mobile test data to address this (which we probably should). But that seems like a bigger task so in this PR I just updated the expected test output. Let me know if you have some other ideas how to address this.

What type of PR is this? (check all applicable)

• 🐛 Bug Fix

Checklist

• 🎉 I have verified that these changes work locally
• 💣 Is your change a breaking change?

Added tests?

• 👍 kind of, I updated the existing integration tests to pass
• 🙅 no, because they aren't needed
• 🙋 no, because I need help

Added to documentation?

• 📓 internal package docs (ymls, macros, readme, if applicable)
• 📕 I have raised a Snowplow documentation PR if applicable (Link here if required)
• 🙅 no documentation needed

[rlh1994]

LGTM, can I just ask you add a changelog entry as we go with each PR please as we've got quite a few changes going into this release. Assuming the tests pass once I fix databricks...

[rlh1994]

LGTM