Fix an issue where the mpris module's tooltip failed to render
when track metadata contained unescaped XML/HTML markup characters.
This occurred because
the mpris module formatted raw strings into the tooltip template
before passing the final string directly to `set_tooltip_markup()`,
triggering GTK/Pango parsing warnings and rendering failures.
Resolve this by wrapping tooltip metadata fields
in `Glib::Markup::escape_text` before formatting,
ensuring Pango-compliant strings are always delivered to the GTK
tooltip markup.
Siriusuna
435c212be1