base16_default: add styles to newer unthemed features (#10858)

* base16_default: add `ui.statusline` for `color-modes`

Signed-off-by: J. Dekker <jdek@itanimul.li>

* base16_default: add `ui.virtual` default

Previously virtual text such as LSP inlay was impossible to distinguish
from 'real' text by default.

Signed-off-by: J. Dekker <jdek@itanimul.li>

---------

Signed-off-by: J. Dekker <jdek@itanimul.li>

base16_theme.toml

@@ -28,6 +28,9 @@
 "label" = "magenta"
 "namespace" = "magenta"
 "ui.help" = { fg = "white", bg = "black" }
+"ui.statusline.insert" = { fg = "black", bg = "green" }
+"ui.statusline.select" = { fg = "black", bg = "blue" }
+"ui.virtual" = { fg = "gray", modifiers = ["italic"] }
 "ui.virtual.jump-label" = { fg = "blue", modifiers = ["bold", "underlined"] }
 "ui.virtual.ruler" = { bg = "black" }