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/2021-04/2021-04-01.json

@@ -0,0 +1,33 @@
+{
+  "dbssticky-data-viz": 30,
+  "drwnio-drwnio": 62,
+  "drwnio-storytelling": 20,
+  "dwelle-hearts": 8,
+  "excacomp-mobile-kit": 18,
+  "excacomp-web-kit": 20,
+  "franky47-apple-devices-frames": 6,
+  "g-script-android": 3,
+  "g-script-charts": 9,
+  "g-script-forms": 58,
+  "g-script-medias": 5,
+  "h7y-dropdowns": 16,
+  "inwardmovement-information-architecture": 37,
+  "jakubpawlina-graphs": 6,
+  "jhoughes-veeam": 65,
+  "kaligule-robots": 45,
+  "lipis-polygons": 4,
+  "lipis-stars": 4,
+  "maeddes-technology-logos": 20,
+  "marcottebear-raspberrypi-zero": 6,
+  "morgemoensch-gadgets": 12,
+  "newbyca-cryptocurrencies": 38,
+  "ocapraro-bubbles": 20,
+  "pclainchard-it-logos": 9,
+  "revolunet-raspberrypi3": 5,
+  "shinkim-presentation-templates": 12,
+  "simalexan-wardley-maps-symbols": 20,
+  "slobodan-aws-serverless": 13,
+  "spfr-lo-fi-wireframing-kit": 38,
+  "youritjang-software-architecture": 110,
+  "youritjang-stick-figures": 48
+}