Set placeholder text in SourceControlInputBox

[huizhougit]

Implement #24090

[mention-bot]

@huizhougit, thanks for your PR! By analyzing the history of the files in this pull request, we identified @dbaeumer to be a potential reviewer.

[huizhougit]

411.44s$ gulp hygiene --silent
Warning: Cannot read property 'flags' of undefined
src/vs/workbench/parts/scm/electron-browser/scmViewlet.ts:13:13:Unused import: 'platform'
The command "gulp hygiene --silent" exited with 1.

Is it failed because of this? But my changes should be nothing about it. Why?

[huizhougit]

@joaomoreno I know this feature is not tagged as help-wanted but my extension relies on it. More important is I hope to do some contribution. Actually, this is my first contribution for vscode, even the first time for open source. Please let me know if I missed anything.

[joaomoreno]

@huizhougit You're not supposed to automatically translate strings. Can you recreate this PR without those translations?

[huizhougit]

@joaomoreno Do you mean I should not change any of the json files?

[joaomoreno]

@huizhougit Exactly.

[huizhougit]

@joaomoreno It's updated

[joaomoreno]

Thanks! 🍻