fix(integ-runner): inconsistent and unexpected CWD in test app execution

[mrgrain]

Fixes an issue with the CWD being inconsistent and unexpected during execution of the test app. Previously we had two different behaviors: For regular execution we would execute the app from the directory of the test file, but for watch we would run it in the actual user's CWD. This is inconsistent behavior making it difficult to write integ test cases than can be executed across all modes. Additionally as reported in #638, languages likes python may rely on CWD to import modules. The CWD changing compared to library code and modes, makes it very difficult to use integ-runner in these languages.

The change aligns the CWD for test app execution to be the current CWD. Given the two existing choices, this is the less arbitrary one and aligns more with running a test app directly (node integ.app-under-test.test.js) would work.

Related to the above change, git operations are now using the -C flag to specify the correct git repository directory instead of the CWD. This ensures integ-runner works correctly even when executed from outside the repository under test. Previously this worked because we change the working directory to the directory containing the test file. However in the error case this printed an incorrect reproduction command that assumed the repro would be run that directory.

Fixes #638

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By submitting this pull request, I confirm that my contribution is made under the terms of the Apache-2.0 license

[codecov-commenter]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 79.47%. Comparing base (d71960e) to head (d83463b).
Report is 1 commits behind head on main.

Additional details and impacted files

@@            Coverage Diff             @@
##             main     #720      +/-   ##
==========================================
- Coverage   79.52%   79.47%   -0.05%     
==========================================
  Files          50       51       +1     
  Lines        7291     7294       +3     
  Branches      826      824       -2     
==========================================
- Hits         5798     5797       -1     
- Misses       1474     1478       +4     
  Partials       19       19              

Flag	Coverage Δ
suite.unit	79.47% <ø> (-0.05%)	⬇️

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