[meta] Path to elastic-package 1.0

[jsoriano]

At some point we should consider elastic-package ready to have a 1.0 version. Let's create a checklist of issues to solve before releasing a 1.0. To decide if something should be done before or after 1.0, think if doing it may introduce breaking changes.

Releasing a 1.0 basically means that we consider elastic-package stable and mature, and we have to be even more considerate with introducing breaking changes.

If we expose something as Go package, we should review also that we are happy with the provided API, but I think we don't expose anything like this here.

Checklist:

• Fully remove deprecated commands related to storage v1 Remove deprecated promote and publish commands #2248 Remove unused code #2335
• Fix issues and redefine profiles and configuration files. Decide what is internal and what is user config. Decide what persists between upgrades and stack operations.
  • Prevent running services of different profiles #962
  • shellinit: use right Kibana and Elasticsearch config #558
  • Profiles: decouple static files from user profiles #557
  • Introduce concept of current profile #361
  • File version management in profiles: Do we want to do it? How? #398
  • Stack state is persisted across restarts #507
• Improve testing coverage (not breaking change, but related to stability/maturity).
  • Allow negative testing in pipeline tests #912
  • Add unit testing for pipeline test runner to cover json decoding and encoding #732
  • System test generate should always have same output #555
• Fix issues related to build
  • elastic-package build command copies hidden files/directories into build directory #1156