Google Ads: Integrate connection check endpoint on Networking layer

[itsmeichigo]

Part of #13139

Description

This PR updates the Networking layer to integrate the endpoint to check the connection of a given site with Google Ads plugin. Changes include:

• New model and mapper for Google ads connection
• New remote for Google ads endpoints.
• Integration of the connection check at path GET wc/gla/ads/connection.

Yosemite update will be done in a separate PR.

Testing steps

Just CI passing should be sufficient.

Screenshots

N/A

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

[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	pr13140-a85b3f8
	Version	19.2
	Bundle ID	com.automattic.alpha.woocommerce
	Commit	a85b3f8
	App Center Build	WooCommerce - Prototype Builds #9743

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

[selanthiraiyan]

Looks good to me. 🚀

I left a question about making this request work for application password login.

[selanthiraiyan]

❓ Should we specify availableAsRESTRequest as true?

I am asking based on the GoogleAdsConnectionMapper being able to parse both with/without data envelope JSON responses.

[itsmeichigo]

Great catch! I added support for REST request in a85b3f8.