Added multiple components, added CodeMirror for body editor and added variable substitution for params and headers

package.json

@@ -13,8 +13,12 @@
   },
   "license": "MIT",
   "dependencies": {
+    "@codemirror/lang-html": "^6.4.11",
+    "@codemirror/lang-json": "^6.0.2",
+    "@codemirror/lang-xml": "^6.1.0",
     "@tauri-apps/api": "^2",
-    "@tauri-apps/plugin-opener": "^2"
+    "@tauri-apps/plugin-opener": "^2",
+    "svelte-codemirror-editor": "^2.1.0"
   },
   "devDependencies": {
     "@internationalized/date": "^3.8.1",