Add rule for redundant string enum values

[jpsim]

enum Numbers: String {
    case one = "one"
    case two = "two"
    case three = "three"
}

is redundant. Could be simply

enum Numbers: String {
    case one
    case two
    case three
}

[marcelofabri]

Should we handle Int enums as well? 🤔

[jpsim]

Maybe. That's not as clear to me.

[marcelofabri]

I'm implementing this and I'm uncertain if we should trigger only if all cases are redundant or if just one case (one violation per case).

This would trigger with the second approach, but not with the first:

private enum ConfigurationKey: String {
    case disabledRules = "disabled_rules"
    case enabledRules = "enabled_rules" // deprecated in favor of OptInRules
    case excluded = "excluded"
    case included = "included"
    case optInRules = "opt_in_rules"
    case reporter = "reporter"
    case useNestedConfigs = "use_nested_configs" // deprecated
    case whitelistRules = "whitelist_rules"
    case warningThreshold = "warning_threshold"
}

[jpsim]

This should trigger only if all cases are redundant.