Public API for creating interceptors, and various utility fns for
common interceptor creation patterns.

Interceptor pattern. Executes a chain of Interceptor functions on a
common "context" map, maintaining a virtual "stack", with error
handling and support for asynchronous execution.

A collection of interceptor helpers.

The usage of the Interceptor API is preferred over the macros
defined in this namespace. Usage of the macro helpers should be
limited to cases where you are porting an existing Pedestal code
base.
 
The helper macros predate the interceptor API and can break AOT
compilation but they are maintained for backwards
compatibility. Refer to
https://github.com/pedestal/pedestal/issues/308 and
https://github.com/pedestal/pedestal/pull/301 for more details about
macro helper issues and the rationale for the Interceptor API.