message: Consolidate the changelog entry for bodystream changes.
diff: - Renamed `GetString()` to `ToString()` in `Azure::Core::DateTime`.
  - Renamed `GetUuidString()` to `ToString()` in `Azure::Core::Uuid`.
  - Renamed `Azure::Core::Details::Version` to `Azure::Core::PackageVersion`.
  -- Moved `BodyStream` and its derived types from `Azure::Core::Http` namespace to `Azure::IO`, and moved the `body_stream.hpp` header from `azure/core/http` to `azure/core/io`.
  +- Moved `BodyStream` and its derived types from `Azure::Core::Http` namespace to `Azure::Core::IO`, and moved the `body_stream.hpp` header from `azure/core/http` to `azure/core/io`.
  - Moved `NullBodyStream` to internal usage only. It is not meant for public use.
  - Removed `LimitBodyStream`.
  - Renamed `AddHeader()` from `Request` and `RawResponse` to `SetHeader()`.
  - Removed `Azure::Core::DateTime::GetRfc3339String()`: `Azure::Core::DateTime::ToString()` was extended to provide the same functionality.
  - Renamed the `Range` type to `HttpRange` within the `Azure::Core::Http` namespace.
  - Moved `Azure::Core::Response<T>` to `Azure::Response<T>`.
  -- Moved types in the `Azure::IO` namespace like `BodyStream` to `Azure::Core::IO`.
  - Moved `Azure::Core::ETag` to `Azure::ETag`.
  - Moved `Azure::Core::DateTime` to `Azure::DateTime`.
  - Renamed `Azure::Core::Http::TokenRequestOptions` to `Azure::Core::Credentials::TokenRequestContext`.
  