feat: add wait for MM package CR readiness (#88)

## Description

Adds a wait action for the MM package CR. This is consistent with the
pattern in uds-core however it runs after the Mattermost chart installs
(meaning the Mattermost chart may still fail waiting on resources like
secrets to exist) however this will catch other issues such as failed
updates to resources or missing resources the chart doesn't directly
depend on like netpols.

## Related Issue

Fixes #N/A

## Type of change

- [ ] Bug fix (non-breaking change which fixes an issue)
- [X] New feature (non-breaking change which adds functionality)
- [ ] Other (security config, docs update, etc)

## Checklist before merging

- [X] Test, docs, adr added or updated as needed
- [X] [Contributor Guide
Steps](https://github.com/defenseunicorns/uds-package-mattermost/blob/main/CONTRIBUTING.md#developer-workflow)
followed

common/zarf.yaml

@@ -21,3 +21,14 @@ components:
         version: 2.6.54
         valuesFiles:
           - ../values/common-values.yaml
+    actions:
+      onDeploy:
+        after:
+          - description: Validate Mattermost Package
+            maxTotalSeconds: 300
+            wait:
+              cluster:
+                kind: Packages
+                name: mattermost
+                namespace: mattermost
+                condition: "'{.status.phase}'=Ready"