Add a quickstart for a single cluster

[maleck13]

What
In a similar vein to what we did with the MGC, I think ideally we would have a quick start script that setup the single cluster environment ready for users to try out.

• local kind cluster,
• installed the required infrastructure (Istio, metallb, cert-manager, olm etc....)
• install the latest release or a specified release of the kuadrant-operator (based on $BRANCH)
• instantiate any needed infra CRs (metallb, clusterissuer etc )
• optionally set up a DNSProvider secret and ManagedZone

Additionally we should provide a new quickstart doc focused around this single cluster setup that provides a walkthrough from deploying a gateway and backed to securing that service with Auth, RateLimits, TLS and then finally brining traffic to the backend with DNSPolicy using a simple routing policy.

Done

• New single cluster quick start script in place that can be executed remotely #370
• New document in place to walkthrough getting setup and trying the different policies #361 (Gh 361 single cluster walk through #362)
• Single Cluster Getting Started (update layout with new sections  docs.kuadrant.io#44)
• New Link aded to the docs.kuadrant.io under Getting Started: single cluster

[maleck13]

see Kuadrant/docs.kuadrant.io#44 for more on the proposed nav layout. We should follow on from the quickstart setup with a link to a modified version of https://github.com/Kuadrant/kuadrant-operator/pull/322/files where we don't need the git clone etc