Add a new .editorconfig and reformat code (#76)

*I'll start working on features and bugfixes after this PR, I promise*
very short summary:
- no more braceless statements
- braces are on new lines now
- `sealed` on everything that can be `sealed`
- no more awkwardly looking alignment of fields/parameters
- no more `Service` suffix on service fields. yeah.
- no more `else`s. who needs them?
- code style is now enforced by CI

---------

Signed-off-by: Octol1ttle <l1ttleofficial@outlook.com>

src/Data/Reminder.cs

@@ -1,7 +1,8 @@
 namespace Boyfriend.Data;
 
-public struct Reminder {
+public struct Reminder
+{
     public DateTimeOffset At;
-    public string         Text;
-    public ulong          Channel;
+    public string Text;
+    public ulong Channel;
 }