Fix broken build by updating fileprivate extension access

[iamgabrielma]

Description

After merging #15891 into trunk it seems a conflict sneaked through, making the build to not compile due to SalesChannelFilter' is not a member type of class 'WooCommerce.FilterOrderListViewModel' error.

This is an update that was made here and was merged into trunk before #15891, without pulling the latests updates from trunk.

Changes

Updated access to analyticsDescription from FilterOrderListViewModel.SalesChannelFilter to SalesChannelFilter

Testing information

• Build should compile. CI should pass.
• Feel free to skip this is you have no POS setup: If you do, you can confirm that tapping on Orders > Filters > Sales Channel > Point of Sale > Show Orders still tracks the event with the sales_channel: pos property, as:

🔵 Tracked orders_list_filter, properties: [plan: , is_wpcom_store: false, blog_id: -1, store_id: c5bd46cc-1804-4f7b-badb-bb98c449127f, site_url: https://indiemelon.mystagingwebsite.com, sales_channel: pos, was_ecommerce_trial: false]

[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	pr15909-93224a1
	Version	22.8
	Bundle ID	com.automattic.alpha.woocommerce
	Commit	93224a1
	Installation URL	5mp8f1f78alq8

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