Admin Page: switch to @wordpress/date in Stats dashboard

[jeherve]

Follow-up to #17321

Changes proposed in this Pull Request:

• This should allow for better translations and date formatting in i18n languages for all date labels in the Stats graph of the Jetpack dashboard.

Before (note the untranslated dates and months)

After

Jetpack product discussion

• Related issues: Admin Page: Move from i18n-calypso to Core functions to handle translations #16481, Update dependency i18n-calypso to v5 #16397

Does this pull request change what data or activity we track or use?

• No

Testing instructions:

You'll need an active site with some stats to be able to test things.

• Go to Jetpack > Dashboard
• Check the different views of the Stats graph (day / week / month)
• Check the dates in all labels and axis; they should be formatted properly.
• Check the "Best day" item at the bottom of the stats graph; that day should be formatted according to the settings under Settings > General.
• If you switch to a different language, that date should change to use the new language.

Proposed changelog entry for your changes:

• Dashboard: improve the display of dates in the Stats graph.

[jetpackbot]

Scheduled Jetpack release: November 3, 2020.
Scheduled code freeze: October 27, 2020

E2E results is available here (for debugging purposes): https://jetpack-e2e-dashboard.herokuapp.com/pr-17343

Thank you for the great PR description!

When this PR is ready for review, please apply the [Status] Needs Review label. If you are an a11n, please have someone from your team review the code if possible. The Jetpack team will also review this PR and merge it to be included in the next Jetpack release.

Generated by 🚫 dangerJS against 9ae0739

[kbrown9]

This works well for me! I tested with a few different languages, and they worked well.

I left an in-line suggestion about a comma in longMonthYearFormat. It's not a blocker, so if you disagree with my suggestion, feel free to merge.

[kbrown9]

This works well for me!