Add time to publication date and remove deprecated date fields

[Cloud11PL]

• Changes 'date' fields in product availability and publication to 'datetime'
• Changes 'date' fields in page availability and publication to 'datetime'
• Replaces deprecated fields with correct ones: availableForPurchase -> availableForPurchaseAt publicationDate -> publishedAt Date -> DateTime

What type of PR is this?

• [ ] 💅 Refactor
• [x] 🌟 Feature
• [ ] 🔥 Bug Fix
• [ ] 🔩 Maintenance
• [ ] 🛠 Workflow CI/CD changes

Related Issues or Documents

• closes #

Usage Instructions, Screenshots, Recordings

Have you written tests?

• [ ] Yes!
• [ ] No... here is why: Writing tests are mandatory, please replace this text with why test are not included in this PR

[Optional] Description

[changeset-bot[bot]]

🦋 Changeset detected

Latest commit: fa14a55d5c732b4bdc2e17e9d280c59af29b8c21

The changes in this PR will be included in the next version bump.

This PR includes changesets to release 1 package

Name	Type
saleor-dashboard	Patch

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[mirekm]

Do we still need to fill the old date fields (availableForPurchase and publicationDate) with the selected date?

[Cloud11PL]

@mirekm No, Saleor syncs old fields with new fields 🙂