Post Publish Metabox: Replace @ with 'at' in the displayed date format

[birgire]

This is a spin-off from ticket #44267

@afercia made a good case here:
https://core.trac.wordpress.org/ticket/44267#comment:10

Not sure using @ adds any value. Instead, I doubt it's announced correctly from assistive technologies in other languages. In Italian, for example, the @ symbol is called chiocciola and its main meaning is "snail" :) Or it's a particular type of stairs.
Firefox and NVDA do read out @ as "chiocciola". This makes sense only in the context of email addresses, where we usually say "xyx chiocciola xyz.com". However, "chiocciola" doesn't make any sense in the context of a date format. I guess this happens also in many other languages.
I guess only in English there's an association between the @ symbol and the word at. I'd tend to think @ doesn't have an universal meaning in the context of dates and it shouldn't be used this way. I'd rather just use the word at like, for example, in the Comments screen.
We should also try to remove @ in all the places in WordPress where it's used for dates, but I guess it should be addressed in a separate ticket.

This ticket focuses only on the post publish metabox. Let's try this one out first and then we can look into the other cases, e.g. revisions.

[SergeyBiryukov]

Looks great to me :)

[audrasjb]

Hi,

As per today's accessibility bug scrub and after some testing, the patch works fine and still applies cleanly, so let's add the commit keyword :)

[afercia]

Related: #47893.

[audrasjb]

Adding back the link to PHP Date documentation

[audrasjb]

@birgire, similarly than in #47893, I propose in 47832.2.diff to re-add the link to PHP Date documentation, so polyglots don't loose that information in the new translation string :)

[birgire]

yes, good idea, thanks @audrasjb

[afercia]

Looks like the patch doesn't apply cleanly any longer, after recent changes.

[afercia]

47832.3.diff​ refreshes the patch.

[SergeyBiryukov]

In 46083:

Accessibility: Posts, Post Types: Replace @ with at in the displayed date format.

The @ symbol makes sense in the context of email addresses, but does not have a universal meaning in the context of dates.

Props birgire, afercia, audrasjb, SergeyBiryukov.
Fixes #47832.