tests: enabling integration tests on windows

[profnandaa]

Depends on #4994 Started addressing #4485

Starting off with this one as a POC on the approach, before we proceed to complete the rest under /frontend/dockerfile.

Tests covered so far:

• [x] /frontend/dockerfile: testEnvEmptyFormatting
• [x] /frontend/dockerfile: testDockerignoreOverride
• [x] /frontend/dockerfile: caseEmptyDestDir