px: fix px.ini creation for persist directive

[nicerloop]

Initialize px.ini before persist directive to avoid creating a px.ini folder. Configure PX_CONFIG environment variable to point to persist/px/px.ini.

Closes https://github.com/ScoopInstaller/Main/issues/5609

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[github-actions[bot]]

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[tech189]

Merging now so that more px.ini folders are not created 😅