Feature 5220

[*] fix return [+] add signer functionality

requested review from @roman.khlopkov

assigned to @roman.khlopkov

added 3 commits

• 1095933d...87a36e7d - 2 commits from branch develop
• 553111f8 - Merge branch 'develop' of gitlab.demlabs.net:cellframe/cellframe-sdk into feature-5220

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closed