Add configuration option for maximum number of fingerprint retries

[coldiron]

Satisfies #792

Adds a new configuration option auth:fingerprint:max_retries with a default of 3, replacing the existing hard-coded value of 3 fingerprint retires.

[alba4k]

Works great, thanks for this change :)))

Also, is there any reason against making something like -1 act as "infinite retries"? I don't think it would be a security hazard, as I don't think brute-forcing fingerprints is a thing anyway

I just noticed that with auth:fingerprint:max_retries = 3 (or any n) I am able to make the authentication fail 4 times (or any n+1). Is this intended? I get why this is (it is trying again 3 times, after the 1st fail) but isn't this unintuitive? I believe it would be better and clearer to rename the option to max_attempts and make it act as a "how many tries the user has" thing.

[PointerDilemma]

Also, is there any reason against making something like -1 act as "infinite retries"? I don't think it would be a security hazard, as I don't think brute-forcing fingerprints is a thing anyway

With this PR 0 should work and -1 too i think?

I just noticed that with auth:fingerprint:max_retries = 3 (or any n) I am able to make the authentication fail 4 times (or any n+1). Is this intended? I get why this is (it is trying again 3 times, after the 1st fail) but isn't this unintuitive? I believe it would be better and clearer to rename the option to max_attempts and make it act as a "how many tries the user has" thing.

@coldiron I think @alba4k is correct on that. Wanna move to max_attempts?

Also let me know if I should finish this up with the changes and wiki MR, or if you want to do it yourself.