show file path for obsolete snapshots

[ron23]

If a test fail due to obsolete snapshot, it's impossible to tell which file has the snapshots.
The filePath flag only address an actual test failure (via asserting testResult.failureMessage).
This PR adds support to show filePath for obsolete snapshots as well.
This tries to solve the same problem reported here #15 but instead of showing the report, simply show the file path for where the error occurred.

The result

$ yarn test:ci 
yarn run v1.21.1
$ JEST_SILENT_REPORTER_SHOW_WARNINGS=true JEST_SILENT_REPORTER_SHOW_PATHS=true <some path> --ci --silent --reporters=jest-silent-reporter --reporters=jest-junit

<the file path with the error>
 › 1 obsolete snapshot found.
error Command failed with exit code 1.
info Visit https://yarnpkg.com/en/docs/cli/run for documentation about this command.

This is the same as #19 but created again against the new main branch

[rickhanlonii]

Works for me!

[rickhanlonii]

Published as 0.4.0