Prepares space for future AI-powered recompose actions for a branch

Adds more item context for new AI-assisted commands to explain unpushed
changes.

(#4443, #4522)

Author: sergeibbb

src/env/node/git/sub-providers/graph.ts

@@ -356,7 +356,9 @@ export class GraphGitSubProvider implements GitGraphSubProvider {
 										: branchIdOfMainWorktree === branchId
 											? '+checkedout'
 											: ''
-								}${branch?.starred ? '+starred' : ''}`,
+								}${branch?.starred ? '+starred' : ''}${branch?.upstream?.state.ahead ? '+ahead' : ''}${
+									branch?.upstream?.state.behind ? '+behind' : ''
+								}`,
 								webviewItemValue: {
 									type: 'branch',
 									ref: createReference(tip, repoPath, {