Support a hidden arg --no-custom-assets that skips loading assets from the cache

src/config.rs

@@ -82,6 +82,10 @@ pub struct Config<'a> {
 
     /// Ranges of lines which should be highlighted with a special background color
     pub highlighted_lines: HighlightedLineRanges,
+
+    /// Whether or not to allow custom assets. If this is false or if custom assets (a.k.a.
+    /// cached assets) are not available, assets from the binary will be used instead.
+    pub use_custom_assets: bool,
 }
 
 #[cfg(all(feature = "application", feature = "paging"))]