updatecli: dynamic specs

[v1v]

What does this PR do?

• Use values.yml to define the configuration to be used when running the updatecli apply, see https://www.updatecli.io/docs/commands/updatecli_apply/#updatecli-apply
• Use scm to fetch the specs in apm and apm-data to fetch all the files under the different folders.
• Use tar with the shell target to untar the file and update those files.

Test

GITHUB_WORKSPACE=/tmp \
  PATH=/opt/homebrew/bin:$PATH \
  GIT_USER="Victor Martinez" \
  GIT_EMAIL="VictorMartinezRubio@gmail.com" \
  GITHUB_TOKEN=$(gh auth token) \
  updatecli apply --config .ci/updatecli/updatecli.d --values .ci/updatecli/values.yml --debug

or without pushing any changes

GITHUB_WORKSPACE=/tmp \
  PATH=/opt/homebrew/bin:$PATH \
  GIT_USER="Victor Martinez" \
  GIT_EMAIL="VictorMartinezRubio@gmail.com" \
  GITHUB_TOKEN=$(gh auth token) \
  updatecli apply --config .ci/updatecli/updatecli.d --values .ci/updatecli/values.yml --push=false --debug

additionally, you can change the org from elastic to your own GitHub avatar.

#1124 was created accordingly

[intuibase]

Hey @v1v
What is the background to this change?
What does this tool give us?

[v1v]

What is the background to this change?

It used to have defined the json-specs and specs from elastic/apm and elastic/apm-data in a static manner, so if for some reason those specs were renamed then they will be required to be changed in the updatecli pipeline. That's not convenience when there are 8 APM Agents.

If you search for Simplify tests specs update from APM to APM agents in this PR you can find the link to the private GitHub repository with the context.

What does this tool give us?

That particular automation was already put in place in #889

Back in the days, we used to centralise all those changes but we came up with the proposal to let the consumers own the automation.