Fix sjis encoding and UI tweaks

[mcoirault]

Ajusted the sjis encoder/decoder to match 81 40 with space, and 81 44 with period.

Added logic+UI to handle icon.sys' linebreak.

Refactored icon_sys_viewer::file_select() and title_cfg_viewer::value_select() into a unified component.

pub fn value_select(
    ui: &mut Ui,
    name: impl Into<String>,
    selected_value: &mut String,
    values: &[String],
) -> Response

The component returns the Response of the underlying text field.

Add warning messages to icon.sys tab to warn against lengthy title/filenames.

Improve icon.sys UI alignment and standardize toolbar sizes across all tabs.