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

webapp/platform/components/README.md

@@ -0,0 +1,24 @@
+# Mattermost Components
+
+The goal of this package is to be a place where components common to all products can be shared.
+
+Currently a work in progress. Next steps involve implementing webpack module federation in the webapp and locking down how the development experience will work for the webapp multi product architecture.
+
+## Usage
+
+Coming soon with multi product architecture.
+
+## Compilation
+
+Building is done using rollup. This must be done so the webapp webpack will pick up the changes. (multi product development experience coming soon)
+
+```bash
+npm run build
+```
+
+or from the root of the webapp with
+
+```bash
+npm run build --workspace=packages/mattermost
+```
+