[AB-xxx] refactoring modmail to offer a feature mode to use threads instead of channels

adding various utilities for thread channels in core
fixing enable feature not showing validation messages
restructuring feature mode collection to be a startup listener, because postconstruct might not have the appropriate values available, and therefore not initialize the map correctly

abstracto-application/abstracto-modules/modmail/modmail-int/src/main/java/dev/sheldan/abstracto/modmail/config/ModMailFeatureConfig.java

@@ -20,6 +20,7 @@ import java.util.List;
 @Component
 public class ModMailFeatureConfig implements FeatureConfig {
 
+    public static final String MOD_MAIL_CLOSING_TEXT_SYSTEM_CONFIG_KEY = "modMailClosingText";
     @Autowired
     private ModMailFeatureValidator modMailFeatureValidator;
 
@@ -33,7 +34,7 @@ public class ModMailFeatureConfig implements FeatureConfig {
 
     @Override
     public List<PostTargetEnum> getRequiredPostTargets() {
-        return Arrays.asList(ModMailPostTargets.MOD_MAIL_PING, ModMailPostTargets.MOD_MAIL_LOG);
+        return Arrays.asList(ModMailPostTargets.MOD_MAIL_PING, ModMailPostTargets.MOD_MAIL_LOG, ModMailPostTargets.MOD_MAIL_CONTAINER);
     }
 
     @Override
@@ -48,12 +49,12 @@ public class ModMailFeatureConfig implements FeatureConfig {
 
     @Override
     public List<FeatureMode> getAvailableModes() {
-        return Arrays.asList(ModMailMode.LOGGING, ModMailMode.SEPARATE_MESSAGE);
+        return Arrays.asList(ModMailMode.LOGGING, ModMailMode.SEPARATE_MESSAGE, ModMailMode.THREAD_CONTAINER);
     }
 
     @Override
     public List<String> getRequiredSystemConfigKeys() {
-        return Arrays.asList("modMailClosingText");
+        return Arrays.asList(MOD_MAIL_CLOSING_TEXT_SYSTEM_CONFIG_KEY);
     }
 
     @Override

abstracto-application/abstracto-modules/modmail/modmail-int/src/main/java/dev/sheldan/abstracto/modmail/config/ModMailMode.java

@@ -9,7 +9,7 @@ import lombok.Getter;
  */
 @Getter
 public enum  ModMailMode implements FeatureMode {
-    LOGGING("log"), SEPARATE_MESSAGE("threadMessage");
+    LOGGING("log"), SEPARATE_MESSAGE("threadMessage"), THREAD_CONTAINER("threadContainer");
 
     private final String key;
 

abstracto-application/abstracto-modules/modmail/modmail-int/src/main/java/dev/sheldan/abstracto/modmail/config/ModMailPostTargets.java

@@ -12,7 +12,11 @@ public enum  ModMailPostTargets implements PostTargetEnum {
     /**
      * The channel to be used to log the contents of closed  mod mail threads
      */
-    MOD_MAIL_LOG("modmailLog");
+    MOD_MAIL_LOG("modmailLog"),
+    /**
+     * The thread used as a container for the modmail threads
+     */
+    MOD_MAIL_CONTAINER("modmailContainer");
 
     private String key;
 

abstracto-application/abstracto-modules/modmail/modmail-int/src/main/java/dev/sheldan/abstracto/modmail/model/template/ModMailClosingHeaderModel.java

@@ -41,4 +41,5 @@ public class ModMailClosingHeaderModel {
     private Boolean silently;
     private User user;
     private Long serverId;
+    private Long modmailThreadId;
 }

abstracto-application/abstracto-modules/modmail/modmail-int/src/main/java/dev/sheldan/abstracto/modmail/model/template/ModMailNotificationModel.java

@@ -8,7 +8,7 @@ import lombok.Getter;
 import lombok.Setter;
 import lombok.experimental.SuperBuilder;
 import net.dv8tion.jda.api.entities.Member;
-import net.dv8tion.jda.api.entities.channel.concrete.TextChannel;
+import net.dv8tion.jda.api.entities.channel.middleman.GuildMessageChannel;
 
 import java.util.List;
 
@@ -33,7 +33,7 @@ public class ModMailNotificationModel extends ServerContext {
      */
     private List<ModMailRole> roles;
     /**
-     * The {@link TextChannel} in which the mod mail thread is handled
+     * The {@link GuildMessageChannel} in which the mod mail thread is handled
      */
-    private TextChannel channel;
+    private GuildMessageChannel channel;
 }

abstracto-application/abstracto-modules/modmail/modmail-int/src/main/java/dev/sheldan/abstracto/modmail/model/template/ModMailThreadContainerValidationErrorModel.java

@@ -0,0 +1,23 @@
+package dev.sheldan.abstracto.modmail.model.template;
+
+import dev.sheldan.abstracto.core.models.ValidationErrorModel;
+import lombok.Builder;
+import lombok.Getter;
+import lombok.Setter;
+
+@Getter
+@Setter
+@Builder
+public class ModMailThreadContainerValidationErrorModel implements ValidationErrorModel {
+    private Long currentChannelId;
+
+    @Override
+    public String getTemplateName() {
+        return "feature_setup_modmail_thread_container_not_setup";
+    }
+
+    @Override
+    public Object getTemplateModel() {
+        return new Object();
+    }
+}