Define new faces for all VC states

[protesilaos]

This allows themes to apply styles that are suitable for Dirvish even when they would not necessarily look good in the modeline where the generic VC faces are present in. For example, the modus-themes do not apply colours to the generic VC modeline faces, though they should apply colour-coding in Dirvish buffers.

[protesilaos]

The idea for this PR is to then be able to customise the themes accordingly (modus-themes and ef-themes). Here is the diff for Modus:

 modus-themes.el | 7 +++++++
 1 file changed, 7 insertions(+)

diff --git a/modus-themes.el b/modus-themes.el
index 9ecc300..604689e 100644
--- a/modus-themes.el
+++ b/modus-themes.el
@@ -2246,6 +2246,14 @@ ;;;;; diredfl
     `(diredfl-symlink ((,c :inherit dired-symlink)))
     `(diredfl-tagged-autofile-name ((,c :inherit (diredfl-autofile-name dired-marked))))
     `(diredfl-write-priv ((,c :foreground ,accent-0)))
+;;;;; dirvish
+    ;; NOTE 2023-06-15: The Dirvish VC faces are used as thin lines to
+    ;; the side of the file listing.  The :foreground effectively is a
+    ;; background, hence the choice of semantic palette mappings.
+    `(dirvish-vc-added-state ((,c :foreground ,bg-added-fringe)))
+    `(dirvish-vc-edited-state ((,c :foreground ,bg-changed-fringe)))
+    `(dirvish-vc-removed-state ((,c :foreground ,bg-removed-fringe)))
 ;;;;; disk-usage
     `(disk-usage-inaccessible ((,c :inherit error)))
     `(disk-usage-percent ((,c :foreground ,accent-0)))

EDIT: remove duplicate line in diff.