Make sure that Cursor::setCurrentFont sets LaTeX language in ERT&friends

Fix issue when language is set to document language instead of
latex_language in ERT and pass thru layouts.

To trigger the issue
1/ select all in a ERT inset
2/ type "abc"
3/ look at code in code preview pane

==> result: the "a" is in document language, the "bc" in LaTeX language
(as should be)

src/Cursor.cpp

@@ -2457,6 +2457,12 @@ void Cursor::setCurrentFont()
 		real_current_font.setLanguage(lang);
 		real_current_font.fontInfo().setNumber(FONT_OFF);
 	}
+
+	// No language in pass thru situations
+	if (cs.paragraph().isPassThru()) {
+		current_font.setLanguage(latex_language);
+		real_current_font.setLanguage(latex_language);
+	}
 }