Add changeset for user-defined scopes for Okta auth

Signed-off-by: ataylorme <andrew@ataylor.me>

.changeset/sharp-wombats-speak.md

@@ -0,0 +1,28 @@
+---
+'@backstage/plugin-auth-backend': minor
+---
+
+Allow user-defined scopes for Okta auth in config yaml
+
+Example `app-config.yaml` excerpt
+
+```yml
+auth:
+  environment: development
+  providers:
+    okta:
+      development:
+        clientId: ${AUTH_OKTA_CLIENT_ID}
+        clientSecret: ${AUTH_OKTA_CLIENT_SECRET}
+        audience: ${AUTH_OKTA_DOMAIN}
+        authServerId: ${AUTH_OKTA_AUTH_SERVER_ID} # Optional
+        idp: ${AUTH_OKTA_IDP} # Optional
+        # https://developer.okta.com/docs/reference/api/oidc/#scope-dependent-claims-not-always-returned
+        scope: openid profile email offline_access groups # Optional
+```
+
+- Accept a new scope option during okta creation with `createAuthProviderIntegration`
+- Pass the user-defined `scope` as an option to `OktaAuthProvider`
+- Add `scope` as an option for `OktaAuthProvider`
+- Set `scope` in `OktaAuthProvider` to the `scope` passed as an `option` or a default of `'openid email profile offline_access'` if a user-defined option is not provided
+- Update the `start` and `refresh` methods to use `scope` from `OktaAuthProvider` rather than `scope` from the request