Add the ability to get config remotely

[petewall]

Notes to reviewers:
The only files I'd like you to review are:

• charts/k8s-monitoring/values.yaml
• charts/k8s-monitoring/templates/collectors/_collector_remoteConfig.tpl
• the files inside of charts/k8s-monitoring/docs/examples/remote-config

So much of the rest are just:

• Refactoring secret handling to work for things other than destinations
• Adding the concept of "platform tests" which are special integration tests that utilize external dependencies like Grafana Cloud.

[skl]

Do these get used somewhere?

[petewall]

Yeah, because this line:

username = {{ include "secrets.read" (dict "object" . "key" "auth.username" "nonsensitive" true) }}

Actually does a ton.

If your values are:

auth: { username = "myuser" }

Then, this will create a K8s secret, with username: myuser and then the alloy config references that secret.

If your values are:

auth: { username = "myuser" }
secret: { embed = true }

Then the string "myuser" is set in the alloy config and no secret is created.

Finally, if your values are:

auth: { usernameFrom = env("MY_USERAME") }

Then it injects the raw string env("MY_USERAME") as the value for the username.

All of this is handled by the template functions.

[petewall]

That's not even mentioning these values:

auth: { usernameKey = "user" }
secret: { create = false, name = mysecret }

Which then references another pre-created secret with a custom key in that secret.