External auth provider secret may be optional

[sweatybridge]

Describe the bug

These fields are not required for native integration

• auth.external.apple.secret
• auth.external.google.secret

To Reproduce

[auth.external.apple]
enabled = true
client_id = "client_id"
secret = ""
redirect_uri = ""
url = ""

Expected behavior Current workaround is to set them to a dummy value.

Screenshots If applicable, add screenshots to help explain your problem.

Desktop (please complete the following information):

• OS: [e.g. iOS]
• Browser (if applicable) [e.g. chrome, safari]
• Version of CLI [e.g. v1.60.0]
• Version of supabase-js (if applicable) [e.g. v2.22.0]
• Version of Node.js (if applicable) [e.g. v16.20.0]

Additional context Add any other context about the problem here.