text: Title: Class-level decorators on Consumer classes do not apply to inherited methods
  Body: **Describe the bug**
  For consumer classes that inherit consumer methods (i.e., methods decorated with `@uplink.get`, `@uplink.post`, etc.) from one or more parent classes, uplink decorators such as`@response_handler` or `@timeout` are not applied to those inherited methods when these decorators are used as class-level decorators. In other words, these decorators are strictly applied to consumer methods that are directly defined on the decorated consumer class.
  
  **To Reproduce**
  Consider the following consumer class:
  ```python
  class GitHub(uplink.Consumer):
      @uplink.get("/users/{username}")
      def get_user(self, username):
          """Get a single user."""
  ```
  
  Create a subclass of `GitHub` and decorate it with any uplink decorator that should propagate to consumer methods when used as a class decorator. For this example, I apply a `@response_handler` that should make any consumer method return the integer `1`, regardless of the actual response returned by the server: 
  ```python
  @response_handler(lambda resp: 1)
  class GitHubSubclass(GitHub):
      pass
  ```
  
  Here’s a quick test that shows that the response handler is not applied to the inherited method (i.e., the assertion fails):
  ```python
  client = GitHubSubclass(...)
  assert github.get_user(“prkumar”) == 1
  ```
  
  **Expected behavior**
  Applying a decorator to a Consumer class should propagate to ALL consumer methods available to that class, including inherited consumer methods.
  
  **Additional context**
  Prior to v0.3.0, the actual behavior reflected the expected behavior detailed above. However, as part of #27, we unnecessarily began restricting the application of class-level decorators to only those consumer methods defined directly on the decorated consumer class. Hence, a fix for this bug should effectively revert the changes made in #27. Notably, this means that the fix should make changes to the function `uplink.helpers.get_api_definitions`. 