Currently on Windows, it's not possible to approve goldens in
`ts-api-guardian`. This is because paths are resolved relatively
to the working directory. In Windows, golden files are resolved
to the actual workspace directory. The current logic tries to
compute a relative path to the runfile from the working directory.
This causes the file paths to have a lot of parent directory
path segments. Eventually, when joined with the build workspace
directory, the paths end up being incorrect. e.g.
```
fileName = ../../../../../../projects/angular/golden/<..>/common.d.ts`
outFile = BUILD_WORKSPACE_DIR + fileName;
```
To fix this, we no longer deal with confusing relative paths, but
instead always use absolute file system paths.
Additionally, this fixes that new goldens are generated at the wrong
location on all platforms.
PR Close#36115
a1e00f82f4