Add more IdPs; remove IdP-specific code

[ericfitz]

• Bitbucket
• GitLab
• Apple

1. Entra
2. Okta
3. Ping
4. OneLogin
5. Google Cloud Identity
6. OCI IAM
7. AWS Identity Center

[ericfitz]

Also GitLab and BitBucket

[ericfitz]

Added svg icons for bitbucket/gitlab/apple.

Significant rework of oauth system has removed most hard-coded values; there's still a little provider-specific code.

Now works with entra (consumer) and entra (SAML).

[ericfitz]

Apple
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