git: Migrate some panel code away from visible_entries (#23251)

To prepare for the introduction of folding in the git panel, these
codepaths need to work with the canonical source of all git status
entries, not just the ones that are visible in the panel.

Release Notes:

- N/A

---------

Co-authored-by: Nate <nate@zed.dev>

crates/git/src/status.rs

@@ -171,7 +171,13 @@ impl FileStatus {
             FileStatus::Tracked(TrackedStatus {
                 index_status,
                 worktree_status,
-            }) => index_status.summary() + worktree_status.summary(),
+            }) => {
+                let mut summary = index_status.to_summary() + worktree_status.to_summary();
+                if summary != GitSummary::UNCHANGED {
+                    summary.count = 1;
+                };
+                summary
+            }
         }
     }
 }
@@ -190,11 +196,23 @@ impl StatusCode {
         }
     }
 
-    fn summary(self) -> GitSummary {
+    /// Returns the contribution of this status code to the Git summary.
+    ///
+    /// Note that this does not include the count field, which must be set manually.
+    fn to_summary(self) -> GitSummary {
         match self {
-            StatusCode::Modified | StatusCode::TypeChanged => GitSummary::MODIFIED,
-            StatusCode::Added => GitSummary::ADDED,
-            StatusCode::Deleted => GitSummary::DELETED,
+            StatusCode::Modified | StatusCode::TypeChanged => GitSummary {
+                modified: 1,
+                ..GitSummary::UNCHANGED
+            },
+            StatusCode::Added => GitSummary {
+                added: 1,
+                ..GitSummary::UNCHANGED
+            },
+            StatusCode::Deleted => GitSummary {
+                deleted: 1,
+                ..GitSummary::UNCHANGED
+            },
             StatusCode::Renamed | StatusCode::Copied | StatusCode::Unmodified => {
                 GitSummary::UNCHANGED
             }
@@ -220,31 +238,19 @@ pub struct GitSummary {
     pub conflict: usize,
     pub untracked: usize,
     pub deleted: usize,
+    pub count: usize,
 }
 
 impl GitSummary {
-    pub const ADDED: Self = Self {
-        added: 1,
-        ..Self::UNCHANGED
-    };
-
-    pub const MODIFIED: Self = Self {
-        modified: 1,
-        ..Self::UNCHANGED
-    };
-
     pub const CONFLICT: Self = Self {
         conflict: 1,
-        ..Self::UNCHANGED
-    };
-
-    pub const DELETED: Self = Self {
-        deleted: 1,
+        count: 1,
         ..Self::UNCHANGED
     };
 
     pub const UNTRACKED: Self = Self {
         untracked: 1,
+        count: 1,
         ..Self::UNCHANGED
     };
 
@@ -254,6 +260,7 @@ impl GitSummary {
         conflict: 0,
         untracked: 0,
         deleted: 0,
+        count: 0,
     };
 }
 
@@ -291,6 +298,7 @@ impl std::ops::AddAssign for GitSummary {
         self.conflict += rhs.conflict;
         self.untracked += rhs.untracked;
         self.deleted += rhs.deleted;
+        self.count += rhs.count;
     }
 }
 
@@ -304,6 +312,7 @@ impl std::ops::Sub for GitSummary {
             conflict: self.conflict - rhs.conflict,
             untracked: self.untracked - rhs.untracked,
             deleted: self.deleted - rhs.deleted,
+            count: self.count - rhs.count,
         }
     }
 }