test: add SCM e2e test

[erha19]

Types

• ⏱ Tests

Background or solution

新增如下测试：

• 打开一个 Git 项目，SCM 面板正确展示当前修改文件状态及数量
• 点击 SCM 面板文件，打开 Diff Edtior，显示异常信息
• 右键 SCM 面板文件，通过 Open File 命令打开源文件

Changelog

[codecov]

Codecov Report

Base: 57.60% // Head: 57.61% // Increases project coverage by +0.00% 🎉

Coverage data is based on head (b4214d9) compared to base (2b415eb).
Patch coverage: 100.00% of modified lines in pull request are covered.

Additional details and impacted files

@@           Coverage Diff           @@
##             main    #1934   +/-   ##
=======================================
  Coverage   57.60%   57.61%           
=======================================
  Files        1286     1286           
  Lines       80509    80534   +25     
  Branches    16851    16855    +4     
=======================================
+ Hits        46381    46397   +16     
- Misses      31044    31052    +8     
- Partials     3084     3085    +1     

Flag	Coverage Δ
jsdom	52.36% <100.00%> (+<0.01%)	⬆️
node	15.88% <50.00%> (+<0.01%)	⬆️

Flags with carried forward coverage won't be shown. Click here to find out more.

Impacted Files	Coverage Δ
...on/src/browser/vscode/contributes/views-welcome.ts	39.58% <100.00%> (+1.28%)	⬆️
packages/scm/src/common/index.ts	100.00% <100.00%> (ø)
packages/utils/src/buffer.ts	30.81% <0.00%> (-4.07%)	⬇️
...ages/file-service/src/node/file-service-watcher.ts	76.59% <0.00%> (-2.39%)	⬇️
packages/search/src/browser/search-tree.service.ts	35.71% <0.00%> (-0.24%)	⬇️
packages/file-service/src/browser/watcher.ts	100.00% <0.00%> (ø)
...file-service/src/node/disk-file-system.provider.ts	78.46% <0.00%> (ø)
...tension/src/browser/vscode/contributes/snippets.ts	93.75% <0.00%> (+0.41%)	⬆️
...es/file-service/src/browser/file-service-client.ts	74.70% <0.00%> (+0.60%)	⬆️
...sion/src/browser/sumi/contributes/browser-views.ts	67.27% <0.00%> (+1.23%)	⬆️
... and 1 more

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[Ricbet]

LGTM