Rearrange directory structure of the repo

[ahg-g]

1. Move pkg/manifests to site-src/manifests
2. Rename pkg/ext-proc to pkg/epp
3. Move pkg/epp/main.go to cmd/epp/main.go

This is more aligned with best practices for go repo structure, and allows us to host other apps, like the bod-to-header translation one: https://kubernetes.slack.com/archives/C071WA7R9LY/p1739569116457569

@danehans @kfswain wdyt?

[ahg-g]

The renaming of ext-proc to epp can be as a followup, not necessarily now just so we don't cause too much conflict with ongoing PRs.

[tchap]

If you don't mind,

/assign

[tchap]

I am not entirely sure why manifests should be in site-src. What is the reasoning there? But no hard feelings really. Not sure what a better place would be. config?

[kfswain]

I think the idea was that the manifests are used in the getting started guide. But I agree that it might be odd to have them show up on the site at their own path.

config does make sense to me
Otherwise the rest of this SGTM

[ahg-g]

yeah, config makes sense too, the main thing was to move out of pkg/