Update bytesfilter.

[piotrm50]

Description of change

Update bytesfilter. This PR builds on top of feat/storable-import and should be merged after.

Type of change

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• Enhancement (a non-breaking change which adds functionality)

How the change has been tested

Describe the tests that you ran to verify your changes.

Make sure to provide instructions for the maintainer as well as any relevant configurations.

Change checklist

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• My code follows 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

[karimodm]

I've just deduplicated the Add and AddIdentifier by creating a common private function.