Make watchers configurable in experiments

[fletchgqc]

CMSB v2.1.0 added support for dynamically configurable watchers. Previously you had to restart the application to change the watchers. See https://codecentric.github.io/chaos-monkey-spring-boot/2.1.0/#_improvements. This links to https://codecentric.github.io/chaos-monkey-spring-boot/2.2.0/#_get_watchers where the endpoints are described.

Chaos Toolkit should support this and implement an action which allows the watchers to be configured in experiments. Currently you can only configure the attacks.