[TASK] Finished Day 13 + some style fixes to make sure eslint is happy enough to deploy to firebase functions

input/day/13-example.http

@@ -0,0 +1,26 @@
+POST http://localhost:5001/advent-of-code-2021-911a8/europe-west1/day-13
+Content-Type: text/plain
+
+6,10
+0,14
+9,10
+0,3
+10,4
+4,11
+6,0
+6,12
+4,1
+0,13
+10,12
+3,4
+3,0
+8,4
+1,10
+2,14
+8,10
+9,0
+
+fold along y=7
+fold along x=5
+
+###