`npm test` crashes on Windows machines (test/run.sh b0rks)

This happens while the Microsoft TypeScript repo gets cloned in the script: when the repo is extracted git fails due to multiple files existing in paths which are 'too long'.

part of what's shown on console:

```
error: unable to create file tests/baselines/reference/project/mapRootAbsolutePathMixedSubfolderSpecifyOutputFileAndOutputDirectory/amd/mapRootAbsolutePathMixedSubfolderSpecifyOutputFileAndOutputDirectory.json: Filename too long
error: unable to create file tests/baselines/reference/project/mapRootAbsolutePathMixedSubfolderSpecifyOutputFileAndOutputDirectory/amd/mapRootAbsolutePathMixedSubfolderSpecifyOutputFileAndOutputDirectory.sourcemap.txt: Filename too long
error: unable to create file tests/baselines/reference/project/mapRootAbsolutePathMixedSubfolderSpecifyOutputFileAndOutputDirectory/node/mapRootAbsolutePathMixedSubfolderSpecifyOutputFileAndOutputDirectory.errors.txt: Filename too long
error: unable to create file tests/baselines/reference/project/mapRootAbsolutePathMixedSubfolderSpecifyOutputFileAndOutputDirectory/node/mapRootAbsolutePathMixedSubfolderSpecifyOutputFileAndOutputDirectory.json: Filename too long
error: unable to create file tests/baselines/reference/project/mapRootAbsolutePathMixedSubfolderSpecifyOutputFileAndOutputDirectory/node/mapRootAbsolutePathMixedSubfolderSpecifyOutputFileAndOutputDirectory.sourcemap.txt: Filename too long
```

The fix is to git clone into a /tmp/xyz directory and then move what we need in here (./test/data/...)

Start in test/run.sh and trace the clone and extraction steps for the Microsoft TypeScript repository. Reproduce the Windows failure, then verify that cloning into a temporary /tmp/xyz directory and moving the needed files into ./test/data allows npm test to complete without filename-too-long errors.

Written by the indexing model from the issue text.