Support the new version of `khiops_env`

[folmos-at-orange]

Description

The khiops_env PR will land soon KhiopsML/khiops#343. We should support the new features of khiops_env and its availability in the conda installation.

Questions/Ideas

• Make the conda detection use khiops_env
  • Conditional code?
• Support all the available variables in the new khiops_env
• "Deprecate" the old code

[popescu-v]

AFAIU, it would suffice to just initialize the relevant attributes of the KhiopsLocalRunner with the values of the appropriate environment variables, as sourced from khiops_env, irrespective of the environment. The new khiops_env now takes care of appropriately setting all relevant environment variables according to the execution environment (Conda, Conda-based, native), in a robust way, without (much) environment-conditional code.

[popescu-v]

Also, as the old code was not part of any official API, all deprecation mechanics would not be necessary IMHO; it would just suffice to remove that (environment-conditional) code.

[popescu-v]

AFAIU, it would suffice to just initialize the relevant attributes of the KhiopsLocalRunner with the values of the appropriate environment variables, as sourced from khiops_env, irrespective of the environment. The new khiops_env now takes care of appropriately setting all relevant environment variables according to the execution environment (Conda, Conda-based, native), in a robust way, without (much) environment-conditional code.

There is one caveat though: we should allow users to override even the variables that are already set in the khiops_env script:

• source khiops_env variables into a specific data structure
• for each of these variables, if the variable is already in os.environ, use the value from the environment. Otherwise, use the khiops_env-defined value.

Thusly, current behavior whereby user-defined environment variables take precedence over default values (henceforth defined in khiops_env) is preserved.