Button to copy the source over translation

Problem/Motivation

Very often, while the translation form element is still empty, translators are copying the source string into the translation form element. Particulary this happens when the source string contains placeholders, HTML markup or complex/multiline strings in order to preserve them.

Proposed resolution

• Add a button between "Source" and "Translation" columns in each row. When the button is pressed, copy the content of source string into the translation form elements
• On languages with more than 2 plural variants, the additional variants should be filled by the unique plural variant from English
• Button should show an arrow (left to right) and a tooltip "Copy source to translation"

Remaining tasks

None.

User interface changes

Button to copy the source string into translation

API changes

None.

Data model changes

None.