Improve messages and behaviour when detecting unhappy installation paths

[tramora]

• in case of major version mismatch, raise immediately an error
• in case of a mix between conda and something else (pip or a cloned source folder), we suggest deactivating the conda env or install the library inside this later
• discourage using system-wide khiops binary and a library inside a conda env

Fixes #515

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TODO Before Asking for a Review

• Rebase your branch to the latest version of dev (or main for release PRs)
• Make sure all CI workflows are green
• When adding a public feature/fix: Update the Unreleased section of CHANGELOG.md (no date)
• Self-Review: Review "Files Changed" tab and fix any problems you find
• API Docs (only if there are changes in docstrings, rst files or samples):
  • Check the docs build without warning: see the log of the API Docs workflow
  • Check that your changes render well in HTML: download the API Docs artifact and open index.html
  • If there are any problems it is faster to iterate by building locally the API Docs

[popescu-v]

IMHO we can discard the .major field in these checks, because if the major fields are different one raises an exception before anyway and never reach these lines. We only reach these lines if the major versions are identical between Core and the Python library.

[popescu-v]

See the comment.
I also think that we should add a test that an exception is raised if the major versions are different between Core and the Python library, in test_khiops_integrations.py plus changes in the CI. Since this test is out of the scope of this PR, I would update issue #382 accordingly with a comment.