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/build/docker/nginx/default.conf

@@ -0,0 +1,38 @@
+upstream app_cluster {
+  server leader:8065 fail_timeout=10s max_fails=10;
+  server follower:8065 fail_timeout=10s max_fails=10;
+  server follower2:8065 fail_timeout=10s max_fails=10;
+}
+
+server {
+  listen 8065;
+
+  location ~ /api/v[0-9]+/(users/)?websocket$ {
+    proxy_set_header Upgrade $http_upgrade;
+    proxy_set_header Connection "upgrade";
+    proxy_http_version 1.1;
+    client_max_body_size 50M;
+    proxy_set_header Host $http_host;
+    proxy_set_header X-Real-IP $remote_addr;
+    proxy_set_header X-Forwarded-For $proxy_add_x_forwarded_for;
+    proxy_set_header X-Forwarded-Proto $scheme;
+    proxy_set_header X-Frame-Options SAMEORIGIN;
+    proxy_buffers 256 16k;
+    proxy_buffer_size 16k;
+    proxy_read_timeout 600s;
+    proxy_pass http://app_cluster;
+  }
+
+  location / {
+    client_max_body_size 50M;
+    proxy_set_header Upgrade $http_upgrade;
+    proxy_set_header Connection "upgrade";
+	proxy_http_version 1.1;
+    proxy_set_header Host $http_host;
+    proxy_set_header X-Real-IP $remote_addr;
+    proxy_set_header X-Forwarded-For $proxy_add_x_forwarded_for;
+    proxy_set_header X-Forwarded-Proto $scheme;
+    proxy_set_header X-Frame-Options SAMEORIGIN;
+    proxy_pass http://app_cluster;
+  }
+}