Add recovery code when we add a yubikey

Descriptive title for this enhancement

The idea is to give recovery code that can be used instead of the yubikey in case the user lost or not have his yubikey with him

Actual behavior

The only way to remove / enter an account without a yubikey if it's enabled is to contact the administrator

Expected behavior

Prevent the case if we lost the yubikey

Step by step description of new behaviour

1. Add the yubikey
2. Generate a recovery code that work only for this user

I think 1 recovery code is enough we not really need to provide a different one for each yubikey

Benefits

Preventing steal / loss of the yubikey

Possible Drawbacks

None

changed milestone to %FusionDirectory 1.4

added PJ1802-0188 plugin-webauthn labels

added 5m of time spent at 2019-12-03

mentioned in issue #6020 (closed)

changed due date to December 18, 2019

mentioned in commit 1e279d8f

hello @MCMic,

some images from gitlab, github, twitter on how they manage this graphically

added 10m of time spent at 2019-12-18

hello @MCMic,

the workflow for recovery code is like this

• recovery code(s) are generated
• show to the user, some like github show a list easy to be copy paste somewhere else
• when the user close the window, they are not visible anymore
• actual recovery codes are stored

each time a code is used it should be removed from the list maybe a counter should tell the user own many valide recovery code are left

added 10m of time spent at 2019-12-18

mentioned in commit f20012b2

mentioned in commit e7e02fc9

added 2h 30m of time spent at 2019-12-18

mentioned in commit 328a1af3

mentioned in commit a6fa5aaf

Works fine from my tests.

added 2h of time spent at 2019-12-19

added To Be Tested label