feat(gui, tauri): Accept --testnet flag, default to mainnet (#106)

This PR tackles #92 

- Add the `tauri-plugin-cli` (only on desktop)
- Check in the frontend if the `--testnet` flag is set. If it's set we pass `testnet=true` to the `initialize_context` command on invokation
- We add the `vite-plugin-top-level-await` to allow top level await in all browsers
- Remove the `bitcoin_confirmation_target` from settings for simplicity

src-tauri/capabilities/default.json

@@ -9,6 +9,7 @@
     "clipboard-manager:allow-write-text",
     "shell:allow-open",
     "store:default",
-    "process:default"
+    "process:default",
+    "cli:allow-cli-matches"
   ]
 }

src-tauri/capabilities/desktop.json

@@ -0,0 +1,11 @@
+{
+  "identifier": "desktop-capability",
+  "platforms": [
+    "macOS",
+    "windows",
+    "linux"
+  ],
+  "permissions": [
+    "cli:default"
+  ]
+}