Consider to make the `Format` taxonomy name plural

[afercia]

When taxonomies register their labels, the name is usually plural and the singular_name is singular. The name default is 'Tags' / 'Categories', while the singular_name default is 'Tag' / 'Category'.

Additional taxonomies register their own labels, for example:
'Navigation Menus' / 'Navigation Menu'
'Link Categories' / 'Link Categoriy'

Plugins often follow the same pattern, for example:
'Project Types' / 'Project Type'
'Project Tags' / 'Project Tag'

Instead, the post_format taxonomy uses a singular form for both the name and singular_name:
'Format' / 'Format'

Seems it works this way since the introduction of these labels in [17261]. Reading the original ticket #16172 seems to me Formats was avoided to not introduce a new string during the "strings-freeze" release period, and it was decided to keep it singular "for now".

While ti's a minor issue, sometimes there's the need to have a proper plural name for Formats, for example when listing programmatically the registered taxonomies.

I'd propose to change the name to a plural form Formats. /cc @SergeyBiryukov

[danieltj]

Updated the format name

[danieltj]

Added a patch to add an s to the string in 43370.diff​.

[joostdevalk]

+1 on fixing this.

[afercia]

Note: patches should be generated from the trunk version. The wp-includes/taxonomy.php file used to generate the attached patch has different spacing compared to the one on trunk, I guess it has been generated from the stable version.

[afercia]

Refreshed patch.

To my knowledge, the taxonomy name is meant to be used for displaying purposes. A couple places in core that would be "affected" are the Menus screen and the Customizer:

[danieltj]

Yes, sorry the patch was generated from the stable version (4.9.4) rather than trunk, apologises. In favour of this changing though for English reasons and consistencies as well. Looks good to me anyway.

[SergeyBiryukov]

In 42755:

Taxonomy: Make the "Format" taxonomy name plural, for consistency with other taxonomies.

Props afercia, danieltj.
Fixes #43370.