Update login and authentication for support sessions

[itsmeichigo]

Closes WOOMOB-62

Description

This PR adds a new option -support-session for the WooCommerce scheme. This is helpful for special settings for login and authentication for support sessions.

More information in p1764067373394239-slack-C03L1NF1EA3.

Test Steps

TC1: Passwordless login

• In Xcode, select WooCommerce > Edit Scheme > Enable -support-session.
• Follow the guide in P91TBi-bVe-p2 to log in to a passwordless account.
• Confirm that the password screen is displayed instead of the magic link request screen.

TC2: WPCom login

• Ensure that -support-session is enabled.
• Log in to a Jetpack store using WPCom credentials.
• Confirm that the app makes requests using Jetpack proxy instead of directly to the remote site.

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 Prototype by scanning the QR code below to install the corresponding build.

	App Name	WooCommerce iOS Prototype
	Build Number	pr16392-049d457
	Version	23.7
	Bundle ID	com.automattic.alpha.woocommerce
	Commit	049d457
	Installation URL	79n5j5ts187ro

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

[adborbas]

LGTM!