feat: validate boolean inputs

[lfleischmann]

Description

Validate boolean inputs instead of assuming all values are valid.

Implementation

Only values that are resolved by strconv.ParseBool without an error are now valid input values.

[FreddyDevelop]

When I try this and use the quickstart app I always get an error at the preflight state when the register_client_capabilities action is used:

{
    "name": "preflight",
    "status": 400,
    "payload": {},
    "csrf_token": "pVj7AjmhgaQvRDbkcCcdZomYrHBJZLWj",
    "actions": {
        "register_client_capabilities": {
            "href": "/login?action=register_client_capabilities%40a3b85827-3a46-4f91-b678-5090e52b6dd9",
            "inputs": {
                "webauthn_available": {
                    "name": "webauthn_available",
                    "type": "boolean",
                    "required": true,
                    "hidden": true,
                    "error": {
                        "code": "value_missing_error",
                        "message": "The value is missing."
                    }
                },
                "webauthn_conditional_mediation_available": {
                    "name": "webauthn_conditional_mediation_available",
                    "type": "boolean",
                    "hidden": true
                },
                "webauthn_platform_authenticator_available": {
                    "name": "webauthn_platform_authenticator_available",
                    "type": "boolean",
                    "hidden": true
                }
            },
            "action": "register_client_capabilities",
            "description": "Send the computers capabilities."
        }
    },
    "error": {
        "code": "form_data_invalid_error",
        "message": "Form data invalid."
    },
    "links": null
}