chore(backend): Drop deprecations (#1899)

* chore(backend): Drop `__unstable_options`

* chore(backend): Drop `frontendApi`

* chore(backend): Drop `clockSkewInSeconds`

* chore(backend): Drop `apiKey` & rename `SetClerkSecretKeyOrAPIKey` to `SetClerkSecretKey`

* chore(backend): Drop `httpOptions`

* chore(backend): Drop image related properties

- `ExternalAccount.picture`
- `ExternalAccountJSON.avatar_url`
- `Organization.logoUrl`
- `OrganizationJSON.logo_url`
- `User.profileImageUrl`
- `UserJSON.profile_image_url`
- `OrganizationMembershipPublicUserData.profileImageUrl`
- `OrganizationMembershipPublicUserDataJSON.profile_image_url`

* chore(backend): Drop `pkgVersion`

* chore(backend): Drop `Organization.getOrganizationInvitationList`

* chore(backend): Drop `orgs` claim

* chore(backend): Cleanup stale TODO commit

* chore(*): Drop using empty frontendApi string on local interstitial

* fix(repo): Fix lint-staged failure for ignored file in shared tests

* chore(backend): Drop `remotePublicInterstitial`

* fix(backend): Replace `as string` with default empty string

The `as string` silents the typescript error but in the runtime
the code fails if the value of `null` or `undefined` is passed
in a function that expects a string to be passed.
Failures may be caused by invoking string specific methods (eg `startsWith`)
which raise a `Cannot read properties of undefined` error.

* chore(repo): Add changeset

.changeset/silly-poems-tease.md

@@ -0,0 +1,26 @@
+---
+'@clerk/backend': major
+---
+
+Drop deprecated properties. Migration steps:
+- use `createClerkClient` instead of `__unstable_options`
+- use `publishableKey` instead of `frontendApi`
+- use `clockSkewInMs` instead of  `clockSkewInSeconds`
+- use `apiKey` instead of  `secretKey`
+- drop `httpOptions`
+- use `*.image` instead of
+    - `ExternalAccount.picture`
+    - `ExternalAccountJSON.avatar_url`
+    - `Organization.logoUrl`
+    - `OrganizationJSON.logo_url`
+    - `User.profileImageUrl`
+    - `UserJSON.profile_image_url`
+    - `OrganizationMembershipPublicUserData.profileImageUrl`
+    - `OrganizationMembershipPublicUserDataJSON.profile_image_url`
+- drop `pkgVersion`
+- use `Organization.getOrganizationInvitationList` with // TODO
+- drop `orgs` claim (if required, can be manually added by using `user.organizations` in a jwt template)
+- use `localInterstitial` instead of `remotePublicInterstitial` / `remotePublicInterstitialUrl`
+
+Internal changes:
+- replaced error enum (and it's) `SetClerkSecretKeyOrAPIKey` with `SetClerkSecretKey`