Allow excluding repositories from being processed

[tegioz]

Sometimes a project may want a repository to only be processed by one of the services feeding from the data files.

For example, a project may want to have all their repositories processed by CLOTributor, but only a subset of them by CLOMonitor. This new feature make this configurable by using the exclude field, which accepts a list of services to exclude the repository from (valid values are clomonitor and clotributor at the moment).

In this example, we are requesting that the func repository is not processed by CLOMonitor:

- name: knative
  display_name: Knative
  description: Kubernetes-based platform to build, deploy, and manage modern serverless workloads
  category: serverless
  logo_url: https://raw.githubusercontent.com/cncf/artwork/master/projects/knative/icon/color/knative-icon-color.svg
  devstats_url: https://knative.devstats.cncf.io/
  accepted_at: "2022-03-02"
  maturity: incubating
  repositories:
    - name: docs
      url: https://github.com/knative/docs/
      check_sets:
        - docs
    - name: func
      url: https://github.com/knative/func
      check_sets:
        - code-lite
      exclude:
        - clomonitor

Related to #1070

[tegioz]

/cc @aliok

[aliok]

Added more repos with CLOMonitor disabled here: #1076