pane_frame_style "none" doesn't work when pane_frames is true

To reproduce:

1. Set pane_frames true
2. Set pane_frame_style "none"
3. Start zellij
4. Panes still render with a title line, same as pane_frame_style "titles" (the default) - "none" has no effect

This can be fixed by adding a Some(PaneFrameStyle::None) => PaneFrameStyle::None arm to the match in PaneFrameStyle::from_options (zellij-utils/src/input/options.rs) - it currently only special-cases Full and falls through to Titles for everything else, including an explicit None. pane_frames false works fine since it's handled by an early return above the match.

Introduced in #5318, first released in v0.45.0. I'll open a PR with the fix.