feat: cancel support

[ShubyM]

Adds cancellation support to the web-ui for operations in kubectl-ai. I've been testing this out by creating a namespace with the following configuration:

kubectl create namespace ns-stuck && kubectl -n ns-stuck create configmap blocker --from-literal=note='This ConfigMap will block namespace deletion.' && kubectl -n ns-stuck patch configmap blocker --type=merge -p '{"metadata":{"finalizers":["demo.finalizers.example.com/never-frees"]}}' 

Then asking kubectl-ai to delete the ns-stuck namespace

To cleanup run the following command:

kubectl -n ns-stuck patch configmap blocker --type=merge -p '{"metadata":{"finalizers":[]}}'