Add Time Until Peak Processed SLO-Checker

Adds the Time Until Peak Processed SLO-Checker to Theodolite. Further information can be found in the corresponding thesis.

This SLO-Checker works similar to the existing SLO-Checkers and further details about the usage can be found in the README. The SLO is added as python code and internally into the Theodolite Operator.

An exemplary use of this SLO-Checker in a Benchmark:

- name: "average_lag"
      sloType: "average lag"
      prometheusUrl: "http://prometheus-operated:9090"
      offset: 0
      properties:
        externalSloUrl: "http://localhost:8084"
        consumerGroup: theodolite-uc2-application-0.0.1
        warmup: 120 # in seconds
        beforeWindowLength: 24
        ignoreDuring: 30
        afterWindowLength: 10 
        error: 0.1
        ratio: 10000