feat: Add Flare support

- Add new log channel "flare" and update "stack" channel to use it
- Introduce placeholders for log messages in several channels
- Add processors to "papertrail" and "stderr" channels
- Add `spatie/laravel-ignition` package to composer requirements
- Change `$dontReport` variable to `$dontFlash` in exception handler
- Add `FLARE_KEY` and `BRIDGY_MASTODON_TOKEN` to `.env.github` and `.env.example` files

.env.example

@@ -83,6 +83,7 @@ APP_LOG=daily
 SESSION_SECURE_COOKIE=true
 
 LOG_SLACK_WEBHOOK_URL=
+FLARE_KEY=
 
 FONT_LINK=