Add autopkgtests

Dear team,

this merge request adds a smoke test to check correct startup behaviour of rsakeyfind and tests the retrieval of RSA-keys from process memory dumps created beforehand and provided as test files.

Thanks already in advance for reviewing and maybe incorporating those tests.

Best regards, Jan

P.S.: Please note, that the failing lintian checks seem not to be connected to the changes I submitted. Autopkgtest run fine in the CI-pipeline.