Add stack provider for Elastic Cloud

[jsoriano]

Last piece of #1055.

Checklist:

• More manual testing.
• Integration testing.
• Documentation.
• Papercuts:
  • Hide password from output.
• Sizing of the deployments started.
• What to do with GeoIP?
• Packages system tests.
  • Decouple system tests from local network?
  • Run and enroll local agent?

How to use/test this

• Optional, use a new profile.

elastic-package profiles create <someprofilename> elastic-package profiles use <someprofilename> 

• Export your API Key for Elastic Cloud, obtained from https://cloud.elastic.co/deployment-features/keys.
  • Write it to a file, for example ~/.elastic-cloud.
  • export EC_API_KEY=$(cat ~/.elastic-cloud)
• Start the cluster, you can select a version adding the --version flag.

elastic-package stack up -v --provider cloud 

• Initialize your shell.

eval $(elastic-package stack shellinit) 

• Usual elastic-package commands should work to install and test packages (some things don't work yet).
• Remember to remove the deployment when not using it.

elastic-package stack down 

[sharbuz]

Hi everyone,
Please update the branch because we merged an important change to the main branch: #1347

[elasticmachine]

💚 Build Succeeded

• Buildkite Build
• Commit: 7a3f2f2

History

• 💔 Build #1210 failed 74b5d1e
• 💚 Build #1178 succeeded c61f7db
• 💚 Build #828 succeeded a41b053
• 💚 Build #826 succeeded 42b95a7
• 💚 Build #805 succeeded f71f8cb

cc @jsoriano