Refactored multiple controllers (`AnnotationController`,
`DocumentController`, `ReadOnlyController`, and
`SignatureController`) to use updated claim extension methods
(`ReceiverSignature`, `EnvelopeUuid`, etc.), replacing older,
verbose methods for improved readability and consistency.
Removed the `EnvelopeClaimTypes` class and replaced claim type
constants with `EnvelopeClaimNames`. Simplified claim retrieval
logic in `ReceiverClaimExtensions` by consolidating methods and
removing redundant or unused functionality.
Eliminated the `SignInEnvelopeAsync` method, indicating a shift
away from manual claim management. Performed general cleanup,
including removing obsolete code and improving exception
messages for better debugging context.