Add french keys for Color Theme Application

The wiki used to take the screenshots is in French, but some of the content is still in English language

When editing a color theme, the popup information that appears when hovering a palette is not translated. This is the case for all popups. Also, when editing a color theme, the information that appears in the dialog after clicking on a palette is not translated. This is the case for all dialogs. Please see the example below. Below an example:

Seems to be hardcoded in each theme we have:
./xwiki-platform-core/xwiki-platform-colorthemes/xwiki-platform-colorthemes-ui/src/main/resources/ColorThemes/ColorThemeClass.xml
./xwiki-platform-core/xwiki-platform-colorthemes/xwiki-platform-colorthemes-ui/src/main/resources/ColorThemes/DefaultColorTheme.xml
./xwiki-platform-core/xwiki-platform-colorthemes/xwiki-platform-colorthemes-ui/src/main/resources/ColorThemes/Dusk.xml
./xwiki-platform-core/xwiki-platform-colorthemes/xwiki-platform-colorthemes-ui/src/main/resources/ColorThemes/ColorThemeTemplate.xml
./xwiki-platform-core/xwiki-platform-colorthemes/xwiki-platform-colorthemes-ui/src/main/resources/ColorThemes/Ruby.xml

Images attached