feat: improve policy comma handling

[m-ignatov]

Fix: casbin/jcasbin#413

[casbin-bot]

@tangyang9464 @imp2002 please review

[CLAassistant]

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[hsluoyz]

@m-ignatov plz fix all errors:

[m-ignatov]

@hsluoyz Moving escapeCasbinRule() & escapeSingleRule() to org.casbin.jcasbin.util.Util will clear the errors in the Codebeat scan I guess, but let me know if this change is okay and will proceed.

[hsluoyz]

@m-ignatov

1. Run all tests in your localhost beforehand, don't test it here
2. sign CLA

[m-ignatov]

@hsluoyz

1. Tested and the build seems to pass
2. I have agreed already, not sure why it does not update here:

[m-ignatov]

@hsluoyz it seems the master pipeline has failed deploying the 2.8.0 version to Maven. Could you check?