Backend work to support minimum password complexity (#2965)

* config: Add minimum password complexity option

* PasswordManager: add function for checking if complexity is sufficient

* Enforce password complexity on registration, change and recovery

* cli: Use exit code 1 for weak passwords

This seems preferable to exit code 0, but ideally we should choose one
and document it.

* Expose minimum password complexity score over GraphQL

docs/config.schema.json

@@ -144,7 +144,8 @@
             "version": 1,
             "algorithm": "argon2id"
           }
-        ]
+        ],
+        "minimum_complexity": 3
       },
       "allOf": [
         {
@@ -1507,6 +1508,13 @@
           "items": {
             "$ref": "#/definitions/HashingScheme"
           }
+        },
+        "minimum_complexity": {
+          "description": "Score between 0 and 4 determining the minimum allowed password complexity. Scores are based on the ESTIMATED number of guesses needed to guess the password.\n\n- 0: less than 10^2 (100) - 1: less than 10^4 (10'000) - 2: less than 10^6 (1'000'000) - 3: less than 10^8 (100'000'000) - 4: any more than that",
+          "default": 3,
+          "type": "integer",
+          "format": "uint8",
+          "minimum": 0.0
         }
       }
     },