🚀 Enhancement: [Web] OAuth2 popup/blank flow

### 🔖 Enhancement description ### Description When performing OAuth2 authentication with the Appwrite client SDK, there is currently no way to specify which OAuth flow should be executed. ### Problem This limitation restricts developers to the default behavior, without allowing them to select the most suitable flow for their use case. ### Suggested Enhancement Similar to how msal.js provides flexibility, it would be beneficial if the SDK exposed an option for developers to explicitly choose the OAuth flow required for their application. This would enable greater control and alignment with diverse authentication scenarios. ### 🎤 Pitch I am facing issues with OAuth2 authentication inside an Airtable custom extension. Since Airtable extensions run inside iframes, the current redirect-based OAuth2 flow does not work. For example, Google (and potentially other providers) set the X-Frame-Options: DENY header, which blocks the redirect inside the iframe. Having the ability to select an alternative OAuth flow would solve this issue and make integration in embedded contexts possible. ### 👀 Have you spent some time to check if this issue has been raised before? - [x] I checked and didn't find similar issue ### 🏢 Have you read the Code of Conduct? - [x] I have read the [Code of Conduct](https://github.com/appwrite/.github/blob/main/CODE_OF_CONDUCT.md)