fix: convert cf-kv and excalidraw-libraries from submodules to regular files

- Remove stale cloudflare-worker submodule entry from .gitmodules
- Remove .git dirs from cf-kv and excalidraw-libraries so Git tracks them as regular files
- Fixes 'No url found for submodule path cf-kv' CI error

excalidraw-libraries/stats/2021-04/2021-04-06.json

@@ -0,0 +1,35 @@
+{
+  "dbssticky-data-viz": 23,
+  "drwnio-drwnio": 52,
+  "drwnio-storytelling": 14,
+  "dwelle-hearts": 18,
+  "excacomp-mobile-kit": 11,
+  "excacomp-web-kit": 19,
+  "franky47-apple-devices-frames": 7,
+  "g-script-android": 7,
+  "g-script-charts": 8,
+  "g-script-forms": 43,
+  "g-script-medias": 4,
+  "h7y-dropdowns": 18,
+  "inwardmovement-information-architecture": 34,
+  "jakubpawlina-graphs": 10,
+  "jhoughes-veeam": 31,
+  "kaligule-robots": 11,
+  "lipis-polygons": 4,
+  "lipis-stars": 3,
+  "maeddes-technology-logos": 30,
+  "marcottebear-raspberrypi-zero": 3,
+  "morgemoensch-gadgets": 7,
+  "newbyca-cryptocurrencies": 13,
+  "ocapraro-bubbles": 16,
+  "pclainchard-it-logos": 18,
+  "revolunet-raspberrypi3": 2,
+  "rkjc-arduino-boards": 11,
+  "rkjc-schematic-symbols": 35,
+  "shinkim-presentation-templates": 3,
+  "simalexan-wardley-maps-symbols": 6,
+  "slobodan-aws-serverless": 19,
+  "spfr-lo-fi-wireframing-kit": 35,
+  "youritjang-software-architecture": 119,
+  "youritjang-stick-figures": 55
+}