fonts: restore listing of fonts in trace mode

```
WEZTERM_LOG=wezterm_font=trace,info wezterm
```

will list fonts found in font_dirs and the builtin fonts.
It can't show all fonts found via the system locator, because
that only has an interface for finding fonts by matching name,
not listing all of them.

wezterm-font/src/db.rs

@@ -122,6 +122,7 @@ impl FontDatabase {
 
         let mut db = Self::new();
         db.load_font_info(font_info);
+        db.print_available();
         Ok(db)
     }
 
@@ -129,7 +130,7 @@ impl FontDatabase {
         let mut names = self.by_full_name.keys().collect::<Vec<_>>();
         names.sort();
         for name in names {
-            log::debug!("available font: {}", name);
+            log::debug!("available font: wezterm.font(\"{}\") ", name);
         }
     }
 
@@ -138,6 +139,7 @@ impl FontDatabase {
         load_built_in_fonts(&mut font_info)?;
         let mut db = Self::new();
         db.load_font_info(font_info);
+        db.print_available();
         Ok(db)
     }