broker: tie in with amqp backend

Creates the WorkerRegistry object to
- track alive workers and their metrics
- submit client requests to workers

Creates the Worker object to
- hold a workers metric
- wrap queue interaction for the worker

Creates the Broker object to
- connect the HTTP API call to WorkerRegistry functions

Library wise these changes are included:
- Adds pika as the amqp connection library and bottle to replace the
  comparatively heavy flask and Werkzeug libraries.
  Bottle can be used with less global state and inside a class, which
  allows to track state within class members.

- Introduces structlog, for log messages that can also expose key/value
  pairs for structered logging.

pyproject.toml

@@ -8,13 +8,15 @@ license = "GPL-2.0-only"
 authors = []
 
 [tool.poetry.scripts]
-wgkex-broker = "wgkex.broker.app:app"
+wgkex-broker = "wgkex.broker.app:main"
 
 [tool.poetry.dependencies]
 python = "^3.6"
 PyYAML = "^5.3.1"
-Flask = "^1.1.2"
 voluptuous = "^0.12.0"
+pika = "^1.1.0"
+structlog = "^20.1.0"
+bottle = "^0.12.19"
 
 [tool.poetry.dev-dependencies]
 black = "^20.8b1"