Example KPT package with subpackages

[liamfallon]

This is an example demo package with two levels of subpackages, with the main package and all its subpackages deploying
separate deployments of nginx

The package has the following structure:

main--+--sub1--+--sub1sub1
      |        |
      |        +--sub1sub2
      |
      +--sub2--+--sub2sub1
               |
               +--sub2sub2

[efiacor]

/approve

[nephio-prow]

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