Fix flaky unit tests

[m0nsky]

Changes the following:

• Fixes a typo (FirstTargetFrameworks -> FirstTargetFramework)
• Restored WriteLinesToFile (I think this was accidently removed in this commit, as discussed in discord: 4f3f0ed)
• Now also checks if the deps folder exists, so if release_id.txt gets written after building the project, but we delete the deps folder (but keep the txt file in place), it's still going to re-download and unzip the deps

Ran the tests 8 times on my fork and didn't manage to reproduce the failing tests.