[WCiOS17] Address non-behavioral compiler warnings

[iamgabrielma]

Closes WOOMOB-1004

Description

This PR addresses ~20 of the non-behavioral compiler warnings as part of pre-work for the the app's iOS17 bump:

1. 'public' modifier is redundant for enum declared in a public extension

Removed public access control for an already public extension: 45fea39

2. '@Namespace' used inline will not work unless tagged with '@Previewable' (from macro 'Preview')

Marked previews that use the Namespace tag as @previewable: a3d1440 . This adds an additional iOS17 check for each preview, but all of them will be removed in one go as soon as we bump the minimum target on a separate issue.

Testing information

• App should compile normally
• Run the app in a simulator and physical device, should init normally. Free free to navigate around, but nothing should have changed behavior-wise.
• CI should pass

---

• I have considered if this change warrants user-facing release notes and have added them to RELEASE-NOTES.txt if necessary.

[dangermattic]

	1 Warning
⚠️	View files have been modified, but no screenshot or video is included in the pull request. Consider adding some for clarity.

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[wpmobilebot]

📲 You can test the changes from this Pull Request in WooCommerce iOS Prototype by scanning the QR code below to install the corresponding build.

	App Name	WooCommerce iOS Prototype
	Build Number	pr15981-a3d1440
	Version	22.9
	Bundle ID	com.automattic.alpha.woocommerce
	Commit	a3d1440
	Installation URL	0929s4qok7o4g

Automatticians: You can use our internal self-serve MC tool to give yourself access to those builds if needed.

[iamgabrielma]

Only one review is needed!