Added a label to the index table's "actions" columns

[pangolingo]

The "actions" columns in the collection table did not have any text in the column header cells. This was fine visually because it's a common pattern to use the final cells for action buttons. But people using a screen readers may not have this visual context. By adding a title of "Actions" to the column, this title is now announced by screen readers when moving into that column.

This addresses on of the accessibility issues listed in https://github.com/thoughtbot/administrate/issues/794

[pangolingo]

I'm marking this as a draft PR because I used an LLM to generate translations for the new column. These should be manually checked.

[pablobm]

Any idea on how we can check those translations? 😅

[pangolingo]

I will see if I can crowdsource the translations from my thoughtbot coworkers. We can probably get 70% of them.

[pangolingo]

Running list of validated translations:

ar/Arabic bs/Bosnian ca/Catalan da/Danish de/German: Aktionen en/English: Actions es/Spanish: Acciones fi/Finnish fr/French: Actions id/Indonesian it/Italian: Azioni ja/Japanese ko/Korean: 작업 nl/Dutch pl/Polish pt-BR/Portuguese (Brazil): Ações pt/Portuguese: Ações ru/Russian sl/Slovenian sq/Albanian sv/Swedish: Åtgärder tr/Turkish: İşlemler uk/Ukrainian vi/Vietnamese zh-CN/Chinese (Simplified): 操作 zh-TW/Chinese (Traditional): 操作