Allows the Settings > Hotkeys screen to be localised, including hotkey decriptions, groups and contexts.
The hotkey names are exposed to localisation via KeycodeExts. Hotkey modifiers are similarly exposed via ModifersExts.
The Settings > Input screen has a Zoom Modifier dropdown, which shows the localised modifier name.
The --check-yaml utility command is taught to recognise all hotkey translation, so it can validate their usage.
The terms "width" and "height" are clearer and they match what the values actually represent (window or parent width/height). The YAML changes are generated with the update rule.
Mod metadata, load screens and mod content is all now sourced from ftl files, allowing these items to be translated.
Translations are now initialized as part of ModData creation, as currently they are made available too late for the usage we need here.
The "modcontent" mod learns a new parameter for "Content.TranslationFile" - this allows a mod to provide the path of a translation file to the mod which it can load. This allows mods such as ra, cnc, d2k, ts to own the translations for their ModContent, yet still make them accessible to the modcontent mod.
CheckFluentReference learns to validate all these new fields to ensure translations have been set.
PARENT_TOP and PARENT_LEFT should be 0 so they are not very useful substitutions. They are replaced with 0 or removed if that was the whole value for a field.
The production palette in RA is assembled from a foreground and a background. The foreground provides most of the visible graphics (such as the metallic chrome) but it has to let clicks go through to the production icons. The background is the one that has to stop the clicks then but it was not wide enough (because the art is only for the background behind production icons and not the whole chrome). Trying to fix that by wrapping the image in wider container that has `ClickThrough` set to `false` revealed that there is a bug with the cloning logic for `ContainerWidget`. It simply did not copy the `ClickThrough` field and it was always `true` for cloned widgets. So the value in YAML was lost when the template was cloned.
