[Woo POS] MVP analytics: Track temaining MVP events and properties

[iamgabrielma]

Closes: #15150
Closes: #15057

Changes

• update exit_menu_item_tapped and exit_confirmed
• add back_to_checkout_from_cash
• add interaction_with_customer_started

Description

Testing information

• pos_back_to_checkout_from_cash:

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

• pos_interaction_with_customer_started

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

Screenshots

---

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

Reviewer (or Author, in the case of optional code reviews):

Please make sure these conditions are met before approving the PR, or request changes if the PR needs improvement:

• The PR is small and has a clear, single focus, or a valid explanation is provided in the description. If needed, please request to split it into smaller PRs.
• Ensure Adequate Unit Test Coverage: The changes are reasonably covered by unit tests or an explanation is provided in the PR description.
• Manual Testing: The author listed all the tests they ran, including smoke tests when needed (e.g., for refactorings). The reviewer confirmed that the PR works as expected on all devices (phone/tablet) and no regressions are added.

[dangermattic]

	1 Error
🚫	Please ensure the PR has the category: tracks label.

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

	2 Messages
📖	This PR contains changes to Tracks-related logic. Please ensure (author and reviewer) the following are completed: The tracks events must be validated in the Tracks system. Verify the internal Tracks spreadsheet has also been updated. Please consider registering any new events. The PR must be assigned the category: tracks label.
📖	This PR is still a Draft: some checks will be skipped.

Generated by 🚫 Danger

[wpmobilebot]

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

	App Name	WooCommerce iOS
	Build Number	pr15151-ee9c9d6
	Version	21.7
	Bundle ID	com.automattic.alpha.woocommerce
	Commit	ee9c9d6
	App Center Build	WooCommerce - Prototype Builds #12972

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