feat: slack-app can now post to both tagged and default channel (#4520)

Currently the slack-app addon only posts to either the tagged channel
for the feature or the default channels. This PR adds a new field that
will allow you to configure the addon to post to both the default
channels and the tagged channel (s)

src/lib/addons/slack-app-definition.ts

@@ -57,6 +57,14 @@ const slackAppDefinition: IAddonDefinition = {
             required: false,
             sensitive: false,
         },
+        {
+            name: 'alwaysPostToDefault',
+            displayName: 'Always post to default channels',
+            description: `If set to 'true' or 'yes', the app will always post events to the default channels, even if the feature toggle has slack tags`,
+            type: 'text',
+            required: false,
+            sensitive: false,
+        },
     ],
     events: [
         FEATURE_CREATED,

src/lib/addons/slack-app.ts

@@ -23,6 +23,7 @@ import { IEvent } from '../types/events';
 interface ISlackAppAddonParameters {
     accessToken: string;
     defaultChannels: string;
+    alwaysPostToDefault: string;
 }
 
 export default class SlackAppAddon extends Addon {
@@ -45,16 +46,26 @@ export default class SlackAppAddon extends Addon {
         parameters: ISlackAppAddonParameters,
     ): Promise<void> {
         try {
-            const { accessToken, defaultChannels } = parameters;
+            const { accessToken, defaultChannels, alwaysPostToDefault } =
+                parameters;
             if (!accessToken) {
                 this.logger.warn('No access token provided.');
                 return;
             }
-
+            let postToDefault =
+                alwaysPostToDefault === 'true' || alwaysPostToDefault === 'yes';
+            this.logger.debug(`Post to default was set to ${postToDefault}`);
             const taggedChannels = this.findTaggedChannels(event);
-            const eventChannels = taggedChannels.length
+            let eventChannels: string[];
+            if (postToDefault) {
+                eventChannels = taggedChannels.concat(
+                    this.getDefaultChannels(defaultChannels),
+                );
+            } else {
+                eventChannels = taggedChannels.length
                     ? taggedChannels
                     : this.getDefaultChannels(defaultChannels);
+            }
 
             if (!eventChannels.length) {
                 this.logger.debug(