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/2021-03/2021-03-18.json

@@ -0,0 +1,31 @@
+{
+  "dbssticky-data-viz": 94,
+  "drwnio-drwnio": 103,
+  "drwnio-storytelling": 23,
+  "dwelle-hearts": 9,
+  "excacomp-mobile-kit": 15,
+  "excacomp-web-kit": 29,
+  "franky47-apple-devices-frames": 8,
+  "g-script-android": 8,
+  "g-script-charts": 17,
+  "g-script-forms": 67,
+  "g-script-medias": 9,
+  "h7y-dropdowns": 17,
+  "inwardmovement-information-architecture": 38,
+  "jakubpawlina-graphs": 9,
+  "lipis-polygons": 8,
+  "lipis-stars": 8,
+  "maeddes-technology-logos": 44,
+  "marcottebear-raspberrypi-zero": 11,
+  "morgemoensch-gadgets": 11,
+  "newbyca-cryptocurrencies": 6,
+  "ocapraro-bubbles": 33,
+  "pclainchard-it-logos": 22,
+  "revolunet-raspberrypi3": 14,
+  "shinkim-presentation-templates": 13,
+  "simalexan-wardley-maps-symbols": 29,
+  "slobodan-aws-serverless": 28,
+  "spfr-lo-fi-wireframing-kit": 72,
+  "youritjang-software-architecture": 220,
+  "youritjang-stick-figures": 85
+}