Remove methods on ClientBulder that don't serve a purpose (#2953)

The `ClientBuilder` struct is gated behind the `gateway` feature, which
means that the client will receive the current application ID over the
gateway when first authenticating. Therefore it doesn't make sense to
set the application ID through the `ClientBuilder` as it will get
overrided anyway.

Also, the `get_token` method is pretty useless because the only source
of the token would be whatever the user would have passed to
`ClientBuilder::new`, meaning they would already have a way to read out
its value.

src/gateway/client/mod.rs

@@ -52,7 +52,6 @@ use crate::http::Http;
 use crate::internal::prelude::*;
 use crate::internal::tokio::spawn_named;
 use crate::model::gateway::GatewayIntents;
-use crate::model::id::ApplicationId;
 #[cfg(feature = "voice")]
 use crate::model::id::UserId;
 use crate::model::user::OnlineStatus;
@@ -109,26 +108,6 @@ impl ClientBuilder {
  }
  }
 
- /// Gets the current token used for the [`Http`] client.
- #[must_use]
- pub fn get_token(&self) -> &str {
- self.http.token()
- }
-
- /// Sets the application id.
- pub fn application_id(self, application_id: ApplicationId) -> Self {
- self.http.set_application_id(application_id);
-
- self
- }
-
- /// Gets the application ID, if already initialized. See [`Self::application_id`] for more
- /// info.
- #[must_use]
- pub fn get_application_id(&self) -> Option<ApplicationId> {
- self.http.application_id()
- }
-
  /// Sets the global data type that can be accessed from [`Context::data`].
  pub fn data<D: std::any::Any + Send + Sync>(mut self, data: Arc<D>) -> Self {
  self.data = Some(data);