chore: proposal for exposing Sidecar configuration

[sumo-drosiek]

I would like to start discussion, and feel this seems good way as it is easy to comment specific parts of document as well as full document itself. I wanted to avoid working in external doc

[kkujawa-sumo]

Example TailingSidecarConfig with options to configure sidecar, example structure with sidecar key added:

apiVersion: tailing-sidecar.sumologic.com/v1
kind: TailingSidecarConfig
metadata:
  name: tailingsidecar-sample
spec:
  sidecar:
    config:
      # configuration which will be added to ConfigMap created by TailingSidecar Operator
    container:
      image: {}
      command: ""
      resources: {}
      # the rest of configuration options for Container Spec https://kubernetes.io/docs/reference/generated/kubernetes-api/v1.22/#container-v1-core     
  annotationsPrefix: tailing-sidecar.sumologic.com
  podSelector:
    matchLabels:
      tailing-sidecar: "true"
  configs:
    sidecar-0:
      volumeMount:
        name: varlog
        mountPath: /var/log
      path: /var/log/example0.log
      annotations:
        sourceCategory: sourceCategory-0
        annotation-0: "true"
    sidecar-1:
      volumeMount:
        name: varlog
        mountPath: /var/log
      path: /var/log/example1.log
      annotations:
        sourceCategory: sourceCategory-1
        annotation-1: "true"
    sidecar-2:
      volumeMount:
        name: varlogconfig
        mountPath: /varconfig-new-dir/log
        readOnly: true
        mountPropagation: HostToContainer
      path: /varconfig-new-dir/log/example2.log
      annotations:
        sourceCategory: sourceCategory-2
        annotation-2: "true"