Insert missing namespace declarations for KMZ files

[njrivera]

A function called insertNamespaces was added to the last release which added missing namespace declarations #5860. However, this worked only for KML files so for this PR I just added a call to the function when loading KMZ files as well, along with another test and test file.

[cesium-concierge]

@nrivera-Novetta, thanks for the pull request! Maintainers, we have a signed CLA from @nrivera-Novetta, so you can review this at any time.

⚠️ I noticed that CHANGES.md has not been updated. If this change updates the public API in any way, fixes a bug, or makes any non-trivial update, please add a bullet point to CHANGES.md and comment on this pull request so we know it was updated. For more info, see the Pull Request Guidelines.

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[pjcozzi]

Great, thanks @nrivera-Novetta! @tfili could you take a quick look?

[tfili]

Looks fine to me besides the conflicts in CHANGES.md. Thanks @nrivera-Novetta . Once you fix the conflicts I'll merge it.

[hpinkos]

@tfili I went ahead and fixed that conflict

[hpinkos]

Thanks for fixing this @nrivera-Novetta!