Package Zip and manifest validation on build

[dazinator]

On project build, we can validate the manifest file (I already have a seperate library to do this) and fail the build if it's invalid. Can also write warnings and info for common things based on best practices (providing owner, license info etc).

If the manifest file is valid, can proceed to validate it against the contents of the zip. For example if the manifest has files specified that don't exist in the zip, we can fail the build with appropriate errors.