feat: YAML config support

[disq]

to go with cloudquery/cq-provider-sdk#332 and cloudquery/cloudquery#887

go run main.go init k8s --config config.yml creates this:

cloudquery:
    providers:
        - name: k8s
          version: latest
    connection:
        type: postgres
        username: postgres
        password: pass
        host: localhost
        port: 5432
        database: postgres
        sslmode: disable
providers:
    # provider configurations
    - name: k8s
      # Optional. Set contexts that you want to fetch. If it is not given then all contexts from config are iterated over.
      # contexts:
      #   - YOUR_CONTEXT_NAME1
      #   - YOUR_CONTEXT_NAME2
      #  
      # list of resources to fetch
      resources:
        - apps.daemon_sets
        - apps.deployments
        - apps.replica_sets
        - apps.stateful_sets
        - batch.cron_jobs
        - batch.jobs
        - core.endpoints
        - core.limit_ranges
        - core.namespaces
        - core.nodes
        - core.pods
        - core.resource_quotas
        - core.service_accounts
        - core.services
        - networking.network_policies
        - rbac.role_bindings
        - rbac.roles