Support flag overrides

Changelog

You can now do things like:

k3sup app install openfaas --load-balancer --basic-auth=false

./bin/k3sup-darwin app install openfaas --help
Install openfaas

Usage:
  k3sup app install openfaas [flags]

Examples:
  k3sup app install openfaas --loadbalancer

Flags:
  -a, --basic-auth         Enable authentication (default true)
  -h, --help               help for openfaas
  -l, --load-balancer      Add a loadbalancer
  -n, --namespace string   The namespace for the core services (default "openfaas")

Get it

curl -SLsf https://get.k3sup.dev | sudo sh