Support more pages in authgear.open()

**Problem**

```
import authgear, { Page } from "@authgear/web";

const openSettings = () = {
authgear.open(Page.Settings)
}
```

Only `Identities` and `Settings` is supported in the `Pages` enum. Users can construct their own path but it'd be easier if the SDK just provide the value.

**Appetite**
0.5

**Solution**

Add the following pages:

* Add identity / remove identity
* 2FA
* Biometric
* passkey
* password
* profile
* sessions

Start in the web SDK at authgear.open() and the Pages enum, comparing the existing Identities and Settings entries. Verify the paths for add/remove identity, 2FA, biometric, passkey, password, profile, and sessions, then confirm each page can be opened through the enum.

Written by the indexing model from the issue text.