Add discovery fields and tests for content packages

[mrodm]

Part of elastic/package-spec#351

Added tests related to content packages and the new discovery fields into the BasePackage manifest definition.

Tested also running locally Elastic Package Registry:

# use test package from package-spec repository
cd /path/to/package-spec/
cd test/packages/good_content
elastic-package build

docker build --build-arg GO_VERSION="$(cat .go-version)" --rm -t docker.elastic.co/package-registry/package-registry:test .
docker run --rm -it -p 8080:8080 -v /path/to/package-spec/build/packages:/packages/package-registry docker.elastic.co/package-registry/package-registry:main

curl "http://localhost:8080/search?type=content&all=true&prerelease=true"
curl "http://localhost:8080/search?type=content&package=good_content&prerelease=true"
curl "http://localhost:8080/search?package=good_content&prerelease=true"

[mergify]

⚠️ The sha of the head commit of this PR conflicts with #1221. Mergify cannot evaluate rules on this PR. ⚠️

[jsoriano]

👍

[elasticmachine]

💚 Build Succeeded

• Buildkite Build
• Commit: b45bbb8

History

• 💚 Build #692 succeeded 23e4dc3
• 💚 Build #687 succeeded d3b244c
• 💚 Build #686 succeeded e014afb

cc @mrodm