Broken out of
DSS-1973: Create the DebianDpkgSigSigner class with mocked signing.
- Refactoring: extract base class from OpenPGPSigner to use also with the new signer in this ticket: BaseOpenPGPSigner [x] VS
- Create the DebianDpkgSigSigner extending the BaseOpenPGPSigner but don't implement the signing yet. [x] VS
- Implement signing of a hardcoded manifestfile (_gpgbuilder) [x] VS
- At this point the results from this signer will be a clear-text signature of the hardcoded manifest (later the input should be a Debian file and the output a modified Debian file with the signed manifest added but for that Debian parsing/writing needs to be implemented). [x] VS