This pull request restructures internal XML import handling to make the code easier to maintain. It does not introduce new features or remove existing behavior, so business impact should be minimal while improving future development reliability.

Follows odoo/odoo#27383 with more refactorings & cleanups of `import_xml.rng` and the corresponding Python code.

As of the PR creation, this only contains (incomplete/wip) refactorings, not new features or deprecations/removals.

This change reorganizes part of Odoo's web client action handling to make the code easier to maintain and evolve. It should not noticeably change day-to-day user workflows, but it can help reduce future development complexity in the web interface.

Description of the issue/feature this PR addresses:

Current behavior before PR:

Desired behavior after PR is merged:




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