Select method to create cluster via button dropdown

[mendaomn]

Description

This PR adds a dropdown button to pick the source from which to create a cluster. It replaces the Source section of the wizard.

It builds upon the work done with #93
Closes #32
Closes #34

A follow up PR will remove the inactive code of the Source page

Changes

• remove source from the steps of the wizard
• add dropdown button to /clusters page
• align e2e tests

How Has This Been Tested?

• manually
  • uploaded a template, checked that the final config matches with the uploaded one
  • create from cluster, checked that the final config matches with the source cluster
• e2e tests

PR Quality Checklist

• I added tests to new or existing code
• I removed hardcoded strings and used react-i18next library (useTranslation hook and/or Trans component), see an example here
• I made sure no sensitive info gets logged at any time in the codebase (see here) (e.g. no user info or details, no stacktraces, etc.)
• I checked that infrastructure/update_infrastructure.sh runs without any error
• I checked that npm run build builds without any error
• I checked that clusters are listed correctly
• I checked that a new cluster can be created (config is produced and dry run passes)
• I checked that login and logout work as expected

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[mtfranchetto]

LGTM! Just do a round of tests when editing a cluster since it has been affected too by the changes