Adds eligibility check to prevent orphaned DOM from rendering

[mtbottens]

PR Summary:

Adds a condition around the newly introduced standalone sign in button on the account login page.

Why are these changes introduced?

If a merchant has sign in with Shop disabled for customer sign ins, we should not render the login button. This was handled in the backend by an eligibility check, but a theme developer wouldn't have the ability to use this condition.

What approach did you take?

Use the login_with_shop_classic_customer_accounts? feature to hide the elements. This condition has been around for 16 months now, but not sure how widespread its usage is.

Other considerations

Decision log

#	Decision	Alternatives	Rationale	Downsides
1

Visual impact on existing themes

If a merchant has sign in with Shop setting disabled, we will not render the "or" text, as well as the login button.

Testing steps/scenarios

• Visit the sign in page
• The sign in button AND the or text should not display.

Demo links

• Store

Checklist

• Added PR summary for release notes
• Requested review from UX (Only for changes that are affecting the experience or perceivable visual details)
• Created a ticket for the help.shopify.com documentation team about updates to theme settings. (Internal-only task)
• Followed theme code principles
• Linted with Theme Check
• Tested on mobile
• Tested on multiple browsers
• Tested for accessibility