fix: ensure patch utility is gnu version

[curbengh]

• Ready for review
• Follows CONTRIBUTING rules
• Reviewed by Snyk internal team

What does this PR do?

This pull adds a check to test whether patch binary is GNU version and outputs an error message if it's not.

How should this be manually tested?

1. Use alpine as CI build environment
2. Install a patch-able node package (e.g. renovate).
3. snyk protect
4. There should be error message Snyk couldn't patch the specified vulnerabilities because GNU's patch is not available. Please install 'patch' and try again..
5. Repeat 1-4 again, but this time with GNU patch installed apk add patch.

Current behavior

• Alpine 3.8: https://gitlab.com/curben/snyk-test/-/jobs/114648947

With this pull

• Alpine 3.8:

  • Without GNU patch
  • With GNU patch

• TrueOS 18.03 (FreeBSD 12):

  • Without GNU patch
    

  • With GNU patch
    

Any background context you want to provide?

Alpine and *BSD ships with BusyBox and BSD versions of patch respectively, which don't support the arguments (i.e. --backup in BusyBox and --verbose in BSD) used by Synk.

This pull helps those OS users to locate the issue, even without --debug.

What are the relevant tickets?

Closes #108 @welwood08

Additional questions

1. This comment mention Snyk ships with patch binary. Please clarify.
2. hasbin() can be replaced by if(error) in exec(). Shall I remove it?
3. Is test case required? not sure what the following line does currently,
   https://github.com/snyk/snyk/blob/c98b8b39779410f70027eab31a97dd910994f332/test/patch-ensure-patch.js#L33

[CLAassistant]

All committers have signed the CLA.

[adrukh]

@weyusi please check a release newer than 1.131.0.
This should not be an issue now that we've moved away from using the binary patch to apply patches.