implement PDP url for product variant

[AlicjaSzu]

I want to merge this change because...

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Pull Request Checklist

1. All visible strings are translated with proper context.
2. All data-formatting is locale-aware (dates, numbers, and so on).
3. The changes are tested.
4. The code is documented (docstrings, project documentation).
5. Changes are mentioned in the changelog.

[netlify]

Deploy preview for saleor-storefront-stage processing.

Building with commit 0f88ecf

https://app.netlify.com/sites/saleor-storefront-stage/deploys/5ec3a8f36c14ef00063127e6

[lgtm-com]

This pull request fixes 1 alert when merging 400c432 into 775ead6 - view on LGTM.com

fixed alerts:

• 1 for Potentially unsafe external link

[lgtm-com]

This pull request fixes 1 alert when merging fe7a578 into 775ead6 - view on LGTM.com

fixed alerts:

• 1 for Potentially unsafe external link

[lgtm-com]

This pull request fixes 1 alert when merging cead073 into 6f5517c - view on LGTM.com

fixed alerts:

• 1 for Potentially unsafe external link

[lgtm-com]

This pull request fixes 1 alert when merging f351aab into 6f5517c - view on LGTM.com

fixed alerts:

• 1 for Potentially unsafe external link

[lgtm-com]

This pull request fixes 1 alert when merging 4092559 into 6f5517c - view on LGTM.com

fixed alerts:

• 1 for Potentially unsafe external link

[lgtm-com]

This pull request fixes 1 alert when merging 501513e into 6f5517c - view on LGTM.com

fixed alerts:

• 1 for Potentially unsafe external link

[lgtm-com]

This pull request fixes 1 alert when merging b2284d0 into 6f5517c - view on LGTM.com

fixed alerts:

• 1 for Potentially unsafe external link

[lgtm-com]

This pull request fixes 1 alert when merging e0da5f4 into 6f5517c - view on LGTM.com

fixed alerts:

• 1 for Potentially unsafe external link

[lgtm-com]

This pull request fixes 1 alert when merging 0f88ecf into d4e122e - view on LGTM.com

fixed alerts:

• 1 for Potentially unsafe external link