feat(vcs): the Push dialog shows the outgoing commits' changed files (#1105)

Below the outgoing commits, the Push dialog lists the files they change: all outgoing commits' combined changes by default, or the selected commit's (Show All Commits goes back). Selecting a file shows its diff beside the tree inside the modal dialog. The multi-repository Push dialog does the same for the selected repository or commit.

src/platform/locales/text/zh.json

@@ -5786,5 +5786,6 @@
   "Syntax errors": "语法错误",
   "Reports code the built-in parser cannot read, in files no language server checks (none is configured for the language, or it is not installed, stopped or crashed). A running language server reports syntax errors itself.": "报告内置解析器无法解析的代码，仅针对没有语言服务器检查的文件（该语言未配置语言服务器，或未安装、已停止、已崩溃）。语言服务器运行时由它自己报告语法错误。",
   "Some items could not be restored": "部分项目无法恢复",
-  "Not in Local History: {names}. They are in the Trash.": "本地历史中没有：{names}。它们在回收站中。"
+  "Not in Local History: {names}. They are in the Trash.": "本地历史中没有：{names}。它们在回收站中。",
+  "Show All Commits": "显示所有提交"
 }