feat: Default project Id - use GOOGLE_APPLICATION_CREDENTIALS first, then GOOGLE_CLOUD_PROJECT

[pawelpasterz]

Fixes #1407

Flank will now use GOOGLE_APPLICATION_CREDENTIALS env first, to parse and get project id. (previously the first one was GOOGLE_CLOUD_PROJECT

Test Plan

How do we know the code works?

1. build flank
2. remember to use the fat jar to launch test runs java -jar ./test_runner/build/libs/flank.jar
3. create dummy echo '{"project_id":"any funny project id here"}' >> test.json
4. export variable export GOOGLE_APPLICATION_CREDENTIALS="$(pwd)/test.json"
5. export variable export GOOGLE_CLOUD_PROJECT="another project id"
6. run any flank test run (within the same terminal window)
7. If you are creative enough you should get 404 (interesting fact: I used ddd project id during local tests and it turned out there is such project, I received 403 instead 😄 ) with a message
   1. 404 -> Flank was unable to find project [id from step 4.]
   2. 403 -> Flank encountered a 403 error when running on project [id from 2.] (from [path to file from 2.])
8. clear export GOOGLE_APPLICATION_CREDENTIALS=
9. similar to 7. except project id should be from 5
10. clear export GOOGLE_CLOUD_PROJECT=
11. run tests, flank should proceed normally

Checklist

• Documented
• Unit tested

[github-actions]

Timestamp: 2020-12-23 13:07:33
Buildscan url for ubuntu-workflow run 440291527
https://gradle.com/s/sbgyufh6ama6e

[pawelpasterz]

@flank-it

[github-actions]

Integration tests succeed, you could see results here