Enhanced Discord Support (#7005)

* Add Discord Provider Prototype

* Add Discord Logo

* Add Plugin to Plugin Manager

* fixed discord auth support and added icon

* add csv role verification

* grab discord server icon and test server id and roles

* subdomain derived from server name

* use discord server specific nickname if available

* Cleanup and comment

* move discord api types to dev deps

* cleanup of server vs default params

* remove commented out lines

* revert envv.development

* revert in vscode

* update yarn lock

* add gif support for discord server icon

* add comment with docs link

* add env section for discord

* fix errors and clarify env

* add new cannot use without

* fix suggestions

.env.sample

@@ -127,6 +127,26 @@ GITHUB_APP_NAME=
 GITHUB_APP_ID=
 GITHUB_APP_PRIVATE_KEY=
 
+# To configure Discord auth, you'll need to create a Discord Application at
+# => https://discord.com/developers/applications/
+#
+# When configuring the Client ID, add a redirect URL under "OAuth2":
+# https://<URL>/api/discord.callback
+DISCORD_CLIENT_ID=
+DISCORD_CLIENT_SECRET=
+
+# DISCORD_SERVER_ID should be the ID of the Discord server that Outline is
+# integrated with. 
+# Used to verify that the user is a member of the server as well as server
+# metadata such as nicknames, server icon and name.
+DISCORD_SERVER_ID=
+
+# DISCORD_SERVER_ROLES should be a comma separated list of role IDs that are
+# allowed to access Outline. If this is not set, all members of the server
+# will be allowed to access Outline.
+# DISCORD_SERVER_ID and DISCORD_SERVER_ROLES must be set together.
+DISCORD_SERVER_ROLES=
+
 # –––––––––––––––– OPTIONAL ––––––––––––––––
 
 # Base64 encoded private key and certificate for HTTPS termination. This is only