Add the preflight agent to the Helm chart

[maelvls]

As part of the beta of our Marketplace solution jetstack-secure-for-cert-manager, want to add the preflight-agent to the Helm chart; the preflight agent image looks like this:

quay.io/jetstack/preflight:v0.1.27

See agent_installation.yaml to see an example of manifest.

Note that we just need the agent to be running; we do not need to create the agent-credentials Secret: we do not want to be sending the user's data to our SaaS Jetstack Secure before the user explicitly accepts to do that.

[simplyzee]

I worked on a helm chart last year for the preflight-agent. This was specifically for our internal clusters but happy for you take it onboard and shape it up for open source use if you like?

https://github.com/jetstack/platform-preflight-agent

[maelvls]

Ohh excellent!

cc @wallrj