Together with application packages, we often need to upload the respective symbols to AppCenter in order to be able to see symbolicated crashes.

The AppCenter API does support symbol file uploads: /v0.1/apps/{owner_name}/{app_name}/symbol_uploads

The path could be a parameter similar as the `pathToApp`:

appCenter apiToken: APPCENTER_API_TOKEN, ownerName: config.organization, appName: config.app, pathToApp: config.package_name pathToSymbols: config.symbol_path

Please add support for symbols, as this is a necessity to make crashes manageable in AppCenter.

Acceptance criteria:

1. Users can enter the path to symbols via the plugin front end.
2. The field is optional
3. Symbols are sent via the API to AppCenter