Add gettext to help tab titles in Remote CSS plugin.

[mayukojpn]

Hi! I found help tab titles aren't translatable in Remote CSS plugin.

[iandunn]

Thanks! The patch looks good to me. I've added it to the merge list.

It'd probably improve readability a bit if each string were a new line, but I can easily do that when I commit it.

[mayukojpn]

Thanks @iandunn ! I changed the style a bit.

[Kenshino]

Wouldn't it make sense to also use sprintf and only write the translation function once? The array should be as simple as possible

[mayukojpn]

@Kenshino We should use gettext one by one so that GlotPress can extract translatable strings. Some plugin authors did same way as you so we couldn't generate .pot file 😞 : ​https://github.com/omise/omise-woocommerce/issues/31

[iandunn]

In 4966:

Remote CSS: Internationalize contextual help tab names

Fixes #2377
Props mayukojpn

[coreymckrill]

In 5118:

WC Remote CSS: Don't use a translated string as an ID

In #4966, making the tab labels translatable introduced the possibility
of a fatal error, because the label became part of the required filename.
This removes the possibility by using a separate ID string for the filename.

See #2377