Extend plugin config validation

Cache validation results
Show field-level errors in UI
Enable manual revalidation
Move PluginConfigService and PluginManagementService into PluginService

plugin-api/src/main/kotlin/de/grimsi/gameyfin/pluginapi/core/Configurable.kt

@@ -4,6 +4,6 @@ interface Configurable {
     val configMetadata: List<PluginConfigElement>
     var config: Map<String, String?>
 
-    fun validateConfig(): Boolean = validateConfig(config)
-    fun validateConfig(config: Map<String, String?>): Boolean
+    fun validateConfig(): PluginConfigValidationResult = validateConfig(config)
+    fun validateConfig(config: Map<String, String?>): PluginConfigValidationResult
 }

plugin-api/src/main/kotlin/de/grimsi/gameyfin/pluginapi/core/PluginConfigValidationResult.kt

@@ -0,0 +1,20 @@
+package de.grimsi.gameyfin.pluginapi.core
+
+data class PluginConfigValidationResult(
+    val result: PluginConfigValidationResultType,
+    val errors: Map<String, String>? = null
+) {
+    companion object {
+        val VALID = PluginConfigValidationResult(PluginConfigValidationResultType.VALID)
+        val UNKNOWN = PluginConfigValidationResult(PluginConfigValidationResultType.UNKNWOWN)
+        fun INVALID(errors: Map<String, String>): PluginConfigValidationResult {
+            return PluginConfigValidationResult(PluginConfigValidationResultType.INVALID, errors)
+        }
+    }
+}
+
+enum class PluginConfigValidationResultType {
+    VALID,
+    INVALID,
+    UNKNWOWN,
+}