Fix RevocationBitmap2022 encoding bug

[UMR1352]

Description of change

Fixes an encoding error in RevocationBitmap2022.

Links to any relevant issues

Fixes issue #1291.
Our implementation of RevocationBitmap2022 had a bug in the code that takes care of encoding the bitmap into a credential service URL. This bug caused a double base64 encoding for the binary list which this PR fixes.
All revocation bitmaps encoded as credential's services before this PR will still be properly decoded and any update on them will fix their encoding.

Type of change

• Bug fix (a non-breaking change which fixes an issue)
• Enhancement (a non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to not work as expected)
• Documentation Fix

How the change has been tested

Added unit tests for both encoding and decoding functions.

Change checklist

• I have followed the contribution guidelines for this project
• I have performed a self-review of my own code
• I have commented my code, particularly in hard-to-understand areas
• I have made corresponding changes to the documentation
• I have added tests that prove my fix is effective or that my feature works
• New and existing unit tests pass locally with my changes

[eike-hass]

Great to see it simplified! Would be good to add some additional information in the PR description and title so it can serve as a reference when linked from the changelog.

[abdulmth]

Looks good to me, thanks for working on it. We still have to clean up the wiki. So maybe we can keep the issue open for now.