Feature request: Import tokens from KeePass database

[lfavole]

Is your feature request related to a problem? Please describe.
Yesterday I decided to install this app and I realized that there is no option to import tokens from a KeePass database. I had to go through every single token and manually copy the secret=XXXX part.

Describe the solution you'd like
It would be a good idea to add an "Import from KeePass database" option. The app asks for the database password and extracts the tokens from all the entries (the otpauth://... URL is located in the otp field of each entry).

Additional context
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