Added and applied styles for private readonly fields, private fields to Extensions and Common folders.

- Some renamings and code cleanups
- Chained method calls, binary expressions and binary patterns will now break into newlines
- Type param constraints and base constructor calls will be on the new line

src/NadekoBot/_Extensions/BotCredentialsExtensions.cs

@@ -0,0 +1,7 @@
+namespace NadekoBot.Extensions;
+
+public static class BotCredentialsExtensions
+{
+    public static bool IsOwner(this IBotCredentials creds, IUser user)
+        => creds.OwnerIds.Contains(user.Id);
+}