Allow treating config fields as sensitive

[Aareksio]

Description

Add sensitive prop to field schema definition. Setting this prop to true should make inputs of type String mask the value to prevent leaking (eg. via screenshots or screenshare). The value is unmasked when user focuses the input to allow for easy editing / copying.

Resolves #1674, hopefully

Screenshots

N/A, didn't test

Additional information

Did not test the change, please test it before merging. Especially the masking / unmasking part. I believe browsers emit focus and blur in all scenarios.

Checklist

• My pull request is not a duplicate
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• I have performed a self-review of my own code