[feat] Support set fileAssociations icon

[wyhaya]

Describe the problem

macOS

The ⁠Info.plist file allows adding the CFBundleTypeIconFile property to specify the icon for associated files. It would be ideal if this could be configured in the ⁠tauri.conf.json file.

<dict>
  <key>CFBundleTypeExtensions</key>
  <array>
    <string>db</string>
  </array>
  <key>CFBundleTypeIconFile</key>
  <string>my-icon.icns</string>
  <key>CFBundleTypeName</key>
  <string>...</string>
</dict>

Describe the solution you'd like

 {
     "fileAssociations": [
         {
             "ext": ["db"],
+            "icon": "./my-icon.icns",
             "name": "SQLite file"
         }
     ]
 }

Alternatives considered

No response

Additional context

No response