refactor(api): consolidate cloud endpoint validators and type definitions

- Move cloud endpoint validator schemas from rest-typings to api implementation
- Inline isCloudConfirmationPollProps, isCloudCreateRegistrationIntentProps, and isCloudManualRegisterProps validators into cloud.ts
- Chain endpoint definitions using fluent API pattern for better organization
- Extract CloudEndpoints type from chained API definition using ExtractRoutesFromAPI utility
- Remove unused CloudRegistrationStatus import and endpoint type definitions from rest-typings
- Update module declaration to extend CloudEndpoints from implementation instead of duplicating types
- Add comment clarifying remaining type exports are for ui-client compatibility

Author: ahmed-n-abdeltwab

.changeset/swift-ways-leave.md

@@ -0,0 +1,6 @@
+---
+'@rocket.chat/rest-typings': minor
+'@rocket.chat/meteor': minor
+---
+
+Migrates cloud endpoint validators (`cloud.manualRegister`, `cloud.createRegistrationIntent`, `cloud.confirmationPoll`) from `rest-typings` into the API implementation, aligning them with the OpenAPI typed route pattern