feat(new source): Initial kubernetes_logs implementation

[MOZGIII]

This PR implements Kubernetes source according to #2222.
There are a few things are different from the RFC:

• the name for the source is kubernetes_logs - it's wasn't properly addressed at the RFC, but the logs and other source kinds for the kubernetes would very likely have very different internal design, so we should probably keep them as separate units; to disambiguate from the very beginning I modified the name to be kubernetes_logs;
• had to bump MSKV to 1.15 - watch bookmarks are introduced in that version, and this is what we want to have to avoid extra desync issues.

Done:

• closes K8s: log file parsing #2626;
• closes K8s: read files from k8s pods #2627;
• closes K8s: ability to quickly iterate and run/test vector in k8s during development #2628;
• closes K8s: an API client for k8s #2629;
• closes K8s: annotate the events originating from kubernetes with pod metadata #2630;
• closes K8s: implement the kubernetes source #2631.

To do (before the merge):

• shutdown logic fix;
• address the fingerprinting issue (The ability to checksum by the first line at the file server #2890);
• move the annotation process to the create_event to optimize out access to the file field;
• ensure that MultiResponseDecoder doesn't leak memory;
• add new dependencies to the environment (minikube, skaffold, etc);
• bookmark parsing error (Parsing error when decoding bookmark Arnavion/k8s-openapi#70).

To do (after the merge):

• more configuration and knobs;
• K8s: integration tests for the k8s source #2632 (integration tests);
• K8s: document the kubernetes source #2633 (documentation).

External refs:

• [EKS]: Support For Kubernetes 1.18 aws/containers-roadmap#809
• Add Monitoring Section to EKS User Guide aws/containers-roadmap#61

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The overall approach was to build highly composable components, so that we can reuse them for further work - like for adding a sidecar-oriented transform for pod annotation, or exclusions based on namespace labels.

[github-actions]

Great PR! Please pay attention to the following items before merging:

Files matching Cargo.lock:

• Has at least one other team member approved the dependency changes?

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[MOZGIII]

The PR is ready for review, please go ahead with it!
There are still a few things left, I'm going to work on those this week. This shouldn't interfere with the review.

[Hoverbear]

I am so pumped!