Mono repo -> Master (#22553)

Combines the following repositories into one:

https://github.com/mattermost/mattermost-server
https://github.com/mattermost/mattermost-webapp
https://github.com/mattermost/focalboard
https://github.com/mattermost/mattermost-plugin-playbooks

server/templates/partials/message_avatar_col.mjml

@@ -0,0 +1,3 @@
+<mj-column css-class="messageAvatarCol">
+    <mj-image css-class="messageAvatar" src="cid:{{.SenderPhoto}}" padding="0px" />
+</mj-column>