Extend JWT Authentication with OAuth Integration [93-3]

[mehalyna]

• Task: Modify the Djoser JWT authentication flow to support OAuth.
• Steps:
  1. Extend the Djoser TokenObtainPairView to handle OAuth logins.
  2. Exchange OAuth authorization code for access token and retrieve the user profile.
  3. Create or update the user and issue JWT tokens.
• Deliverable: OAuth-based JWT token flow integrated with Djoser.

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US #93