Tweaks to kuadrantctl install - error handling for missing deps.

[jasonmadigan]

Added some error handling for missing deps when running kuadrantctl install.

Note: we're installing an earlier version of the operator - I'll submit another PR to update things to install v0.6.1

Testing

# build kuadrantctl
make install

kind create cluster

# cert-manager
kubectl apply -f https://github.com/cert-manager/cert-manager/releases/download/v1.14.3/cert-manager.yaml

# GW API CRDs
kubectl get crd gateways.gateway.networking.k8s.io &> /dev/null || \
  { kubectl kustomize "github.com/kubernetes-sigs/gateway-api/config/crd?ref=v1.0.0" | kubectl apply -f -; }

# Istio
(curl -L https://istio.io/downloadIstio | sh - && cd istio-* && ./bin/istioctl install --set profile=default -y)

# OLM
curl -L https://github.com/operator-framework/operator-lifecycle-manager/releases/download/v0.27.0/install.sh | bash -s v0.27.0

bin/kuadrantctl install

[jasonmadigan]

Maybe we should just link to https://docs.kuadrant.io/getting-started-single-cluster/#prerequisites instead...

[david-martin]

As it stands, the dependency error instructs to 'Please follow the installation guide at..'
If that is and always will be the same as what other docs (like on docs.kuadrant.io) will say, then that seems like a good dev exp as it brings them closer to the solution quicker than having to parse through the prerequisites section of guide that may have multiple prerequisites.

If however it may be different, like specifying a specific version or a specific way of installing, then linking to docs.kuadrant.io is the safest as that is something actively being maintained and tested with each release

[jasonmadigan]

I like your point about getting people to the right information, sooner. I think these looks are generic/non-versioned enough to be quite stable.

[jasonmadigan]

Follow-on: #56