lokal test improvements

[blu-nitro]

• 1. Consolidate and de-duplicate make targets, potentially move to a separate Makefile: consolidate and de-duplicate local-test make targets #12
• 2. Detect debugger problems and abort early -- currently I run into the normal 90 s timeout if the dev device is not recognized by the debugger
• 3. Speed up nitrokey-3-tests -- it currently always re-builds a docker image which is very slow
• 4. Document how to obtain the required binaries from GitHub or the CI and how to build them locally
• 5. Provide scripts/make targets for (4)
• 6. Validate the checksum of all binaries downloaded in the Dockerfile