[operator] - friction on install

[puckpuck]

Ran into 2 friction issues when installing the operator:

1. The operator requires a cert-manager and several cert CRDs to be setup before it can be installed. There are instructions in the readme to do so, forcing the user to go elsewhere, have to install another helm repo or run a kubectl apply script. This makes for a not so great experience. We could clean this up by including the cert-manager as a sub chart, allowing the user to get setup quickly.

2. When installing the chart I came across this error:

√ otel-operator 🤘 : helm install opentelemetry-operator open-telemetry/opentelemetry-operator                                                           
Error: INSTALLATION FAILED: create: failed to create: namespaces "opentelemetry-operator-system" not found

After creating the mentioned namespace it worked fine, but this feels like it should be handled with installation instructions and/or by the Helm chart itself.

[TylerHelmuth]

/cc @Allex1

[Allex1]

@puckpuck Thanks for opening this.

1. I think we should disable cert-manager and use self signed cert by default while deploying cert-manager under a feature flag. Would you be willing to look at this?
2. helm has the --create-namespace flag and we could probably add it in the readme but it's a newer flag and I haven't seen it yet on other helm git repos.