This PR adds more terminal colors that were present in the Zed1 themes
to the Zed2 theme.
Namely, we now have the `dim_` variants for the various ANSI colors and
various `foreground` colors.
Release Notes:
- Improved terminal colors.
This PR removes the `Default` impl for `StatusColors`.
Since we need default light and dark variants for `StatusColors`, we
can't use a single `Default` impl.
Release Notes:
- N/A