Use wp_login_url instead of hardcoding login path

[senadir]

We had wp-login.php hardcoded in our code, this prevented some security plugins from changing its value, plugins like https://wordpress.org/plugins/change-wp-admin-login/ for example, in this pr we use wp_login_url which has a login_url filter.

Fixes #3037

How to test the changes in this Pull Request:

1. In an incognito window and add some products and then go to Checkout.
2. See the login URL, it should take you to wp-login.php?redirect_to=[CURRENT_URL]
3. Enable checkout for users only from WooCommerce -> Settings -> Accounts -> uncheck Allow customers to place orders without an account.
4. Visit Checkout again, the link should do the same.
5. Install and activate https://wordpress.org/plugins/change-wp-admin-login/.
6. Visit Settings -> Permalinks and change the login URL to something else.
7. Do 1,2,3 and 4 again, confirm that your value is respected.

[github-actions]

Size Change: +718 B (0%)

Total Size: 1.11 MB

Filename	Size	Change
build/active-filters-frontend.js	8.78 kB	+24 B (0%)
build/active-filters.js	8.85 kB	+21 B (0%)
build/all-products-frontend.js	31.2 kB	+26 B (0%)
build/all-products.js	35.7 kB	+27 B (0%)
build/all-reviews.js	9.79 kB	+25 B (0%)
build/atomic-block-components/image-frontend.js	1.71 kB	+1 B
build/atomic-block-components/title.js	1.05 kB	-1 B
build/attribute-filter-frontend.js	18.1 kB	+29 B (0%)
build/attribute-filter.js	12.4 kB	+22 B (0%)
build/cart-frontend.js	69 kB	+28 B (0%)
build/cart.js	37.4 kB	+28 B (0%)
build/checkout-frontend.js	84.2 kB	+23 B (0%)
build/checkout.js	40.8 kB	+20 B (0%)
build/featured-category.js	7.72 kB	+23 B (0%)
build/featured-product.js	9.97 kB	+23 B (0%)
build/handpicked-products.js	7.37 kB	+25 B (0%)
build/price-filter-frontend.js	14.4 kB	+25 B (0%)
build/price-filter.js	10.3 kB	+24 B (0%)
build/product-best-sellers.js	7.44 kB	+23 B (0%)
build/product-category.js	8.38 kB	+24 B (0%)
build/product-new.js	7.6 kB	+25 B (0%)
build/product-on-sale.js	7.99 kB	+25 B (0%)
build/product-search.js	3.56 kB	+25 B (0%)
build/product-tag.js	6.52 kB	+26 B (0%)
build/product-top-rated.js	7.57 kB	+24 B (0%)
build/products-by-attribute.js	8.31 kB	+27 B (0%)
build/reviews-by-category.js	11.8 kB	+25 B (0%)
build/reviews-by-product.js	13.4 kB	+23 B (0%)
build/reviews-frontend.js	9.37 kB	+23 B (0%)
build/single-product-frontend.js	34 kB	+29 B (0%)
build/single-product.js	10.1 kB	+26 B (0%)

ℹ️ View Unchanged

Filename	Size	Change
build/atomic-block-components/add-to-cart-frontend.js	8.89 kB	0 B
build/atomic-block-components/add-to-cart.js	7.46 kB	0 B
build/atomic-block-components/add-to-cart~atomic-block-components/button.js	3.16 kB	0 B
build/atomic-block-components/add-to-cart~atomic-block-components/image~atomic-block-components/title.js	335 B	0 B
build/atomic-block-components/button-frontend.js	2.02 kB	0 B
build/atomic-block-components/button.js	835 B	0 B
build/atomic-block-components/category-list-frontend.js	469 B	0 B
build/atomic-block-components/category-list.js	475 B	0 B
build/atomic-block-components/image.js	1.15 kB	0 B
build/atomic-block-components/price-frontend.js	2.1 kB	0 B
build/atomic-block-components/price.js	2.13 kB	0 B
build/atomic-block-components/rating-frontend.js	524 B	0 B
build/atomic-block-components/rating.js	527 B	0 B
build/atomic-block-components/sale-badge-frontend.js	863 B	0 B
build/atomic-block-components/sale-badge.js	864 B	0 B
build/atomic-block-components/sku-frontend.js	389 B	0 B
build/atomic-block-components/sku.js	394 B	0 B
build/atomic-block-components/stock-indicator-frontend.js	568 B	0 B
build/atomic-block-components/stock-indicator.js	571 B	0 B
build/atomic-block-components/summary-frontend.js	918 B	0 B
build/atomic-block-components/summary.js	925 B	0 B
build/atomic-block-components/tag-list-frontend.js	466 B	0 B
build/atomic-block-components/tag-list.js	472 B	0 B
build/atomic-block-components/title-frontend.js	1.22 kB	0 B
build/blocks.js	3.54 kB	0 B
build/editor-rtl.css	13.9 kB	0 B
build/editor.css	13.9 kB	0 B
build/product-categories.js	3.23 kB	0 B
build/style-rtl.css	18 kB	0 B
build/style.css	18 kB	0 B
build/vendors-style-rtl.css	1.03 kB	0 B
build/vendors-style.css	1.03 kB	0 B
build/vendors.js	416 kB	0 B
build/vendors~atomic-block-components/price-frontend.js	5.65 kB	0 B
build/wc-blocks-data.js	7.09 kB	0 B
build/wc-blocks-middleware.js	931 B	0 B
build/wc-blocks-registry.js	2.28 kB	0 B
build/wc-payment-method-bacs.js	790 B	0 B
build/wc-payment-method-cheque.js	787 B	0 B
build/wc-payment-method-cod.js	875 B	0 B
build/wc-payment-method-paypal.js	831 B	0 B
build/wc-payment-method-stripe.js	11.9 kB	0 B
build/wc-settings.js	2.33 kB	0 B
build/wc-shared-context.js	1.53 kB	0 B
build/wc-shared-hocs.js	1.66 kB	0 B

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[Aljullu]

Works like a charm. 👌