General: Fix various issues flagged by the PHPCompatibilityWP PHPCS ruleset.

As part of the continued effort to improve PHP compatibility, the following improvments are being made:

- Removing deprecated PHP `safe_mode` checks not found in bundled external libraries.
- Change the remaining `while` loops using `each()` to `foreach` loops.
- Prevent false positives from being flagged for the `sodium_compat` library being caused by loading this in a non-standard way.
- Add inline comments to not flag deprecated PHP directives in the getID3 library.

Props desrosj, earnjam, dryanpress.
See #49922.
Built from https://develop.svn.wordpress.org/trunk@47735


git-svn-id: https://core.svn.wordpress.org/trunk@47511 1a063a9b-81f0-0310-95a4-ce76da25c4cd