Delete progressviewios.md

[yungsters]

The recommendation since 0.72 has been to use @react-native-community/progress-view, so this page is no longer relevant.

As such, this PR deletes them so that we no longer have to maintain them.

I've also updated the 0.72 blog post to link to the docs at 0.72 instead of next (so that the blog post links don't break when this PR is published).

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[elicwhite]

Build failed because it creates broken links:

11:29:16 AM: Exhaustive list of all broken links found:
11:29:16 AM: - Broken link on source page path = /blog/2023/06/21/0.72-metro-package-exports-symlinks:
11:29:16 AM: -> linking to /docs/0.72/slider
11:29:16 AM: -> linking to /docs/0.72/datepickerios
11:29:16 AM: -> linking to /docs/0.72/progressviewios

[yungsters]

Thanks, I switched to fully-formed URLs.