feat(kubernetes): set kubernetes_ca_cert as sensitive

[haarchri]

Description of your changes

https://crossplane.slack.com/archives/C01TRKD4623/p1690290399596229

building a poc for managing vault config via crossplane, i m trying to deploy this https://marketplace.upbound.io/providers/upbound/provider-vault/v0.1.0/resources/kubernetes.vault.upbound.io/AuthBackendConfig/v1alpha1 resource and was wondering how can we specify spec.forProvider.kubernetesCaCert via a configmap/secret rather than raw values

switched kubernetesCaCert as sensitive - that its possible to set via kubernetes secret

Fixes #

I have:

• Read and followed Crossplane's contribution process.
• Run make reviewable test to ensure this PR is ready for review.

How has this code been tested

create & delete

[mustafaStakater]

Can we add support for specifying kubernetes_ca_cert as configmap,
how long till this gets merged ? thanks

[haarchri]

i checked our providers in crossplane-contrib/provider-aws and upbound/provider-aws both implementing ca_cert in connection secret so i see no need for configmap - and with upjet we have no option for both

[haarchri]

rebased

[mustafaStakater]

what todo if we want to use the kube-root-ca.crt configmap as kubernetes_ca_cert, possible when vault is running on the same cluster as crossplane

[haarchri]

@mustafaStakater today we have not the option to have secret and configmap as ref