[18.0][ADD] purchase_report_discount_visibility

[AungKoKoLin1997]

This module allows hiding the Discount column in the Purchase Order report, either always or only when all order lines have no discount.

@qrtl QT6324

[yostashiro]

I don't think it was necessarily a good move to move the logic from Python to the template, but it's trivial. LGTM.

[kanda999]

Code and functional review.

[OCA-git-bot]

This PR has the approved label and has been created more than 5 days ago. It should therefore be ready to merge by a maintainer (or a PSC member if the concerned addon has no declared maintainer). 🤖

[BhaveshHeliconia]

Code and functional review LGTM!

[HviorForgeFlow]

/ocabot merge nobump

[OCA-git-bot]

On my way to merge this fine PR!
Prepared branch 18.0-ocabot-merge-pr-94-by-HviorForgeFlow-bump-nobump, awaiting test results.

[OCA-git-bot]

@HviorForgeFlow The merge process could not be finalized, because command twine upload --disable-progress-bar --non-interactive --repository-url https://upload.pypi.org/legacy/ -u __token__ odoo_addon_purchase_report_discount_visibility-18.0.1.0.0.2-py3-none-any.whl failed with output:

Uploading distributions to https://upload.pypi.org/legacy/
Uploading 
odoo_addon_purchase_report_discount_visibility-18.0.1.0.0.2-py3-none-any.whl
�[33mWARNING �[0m Error during upload. Retry with the --verbose option for more details. 
�[31mERROR   �[0m HTTPError: 429 Too Many Requests from https://upload.pypi.org/legacy/  
         Too Many Requests