Feature/graphql server settings (#629)

* Add "uiName" to WebUI enum

* Add "Custom" WebUI to enum

* Rename "WebUI" enum to "WebUIFlavor"

* Add "WebUIInterface" enum

* Add query for server settings

* Add mutation for server settings

* Add mutation to reset the server settings

* Only update the config in case the value changed

In case the value of the config is already the same as the new value of the state flow, it is not necessary to update the config file

server/src/main/kotlin/suwayomi/tachidesk/graphql/queries/SettingsQuery.kt

@@ -0,0 +1,9 @@
+package suwayomi.tachidesk.graphql.queries
+
+import suwayomi.tachidesk.graphql.types.SettingsType
+
+class SettingsQuery {
+    fun settings(): SettingsType {
+        return SettingsType()
+    }
+}