Remove deleted files from open editor tabs

[ianyong]

Description

Resolves the following issue that was raised by @zhaojj2209 in #2378:

• If a file tab is open, the tab will remain even if the file is deleted. Note below that the /test folder/test.js tab still exists even though the file no longer exists.
  

Part of #2176.

Type of change

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to not work as expected)
• This change requires a documentation update
• Code quality improvements

How to test

The multiple files mode is not yet ready for production and is disabled programmatically. Enable multiple files mode for testing by changing the condition to false:

frontend/src/pages/playground/Playground.tsx

Lines 603 to 615 in 9bc1140

	const toggleMultipleFilesModeButton = React.useMemo(() => {
	// TODO: Remove this once the multiple file mode is ready for production.
	if (true) {
	return <></>;
	}
	return (
	<ControlBarToggleMultipleFilesModeButton
	isMultipleFilesEnabled={isMultipleFilesEnabled}
	toggleMultipleFilesMode={() => dispatch(toggleMultipleFilesMode(workspaceLocation))}
	/>
	);
	}, [dispatch, isMultipleFilesEnabled, workspaceLocation]);

Then, verify that deleting files or folders from the file system view results in the corresponding editor tabs being closed.

[coveralls]

Pull Request Test Coverage Report for Build 4510868611

• 36 of 39 (92.31%) changed or added relevant lines in 5 files are covered.
• 1 unchanged line in 1 file lost coverage.
• Overall coverage increased (+0.1%) to 35.029%

---

Changes Missing Coverage	Covered Lines	Changed/Added Lines	%
src/commons/fileSystemView/FileSystemViewFileNode.tsx	0	1	0.0%
src/commons/fileSystemView/FileSystemViewDirectoryNode.tsx	0	2	0.0%

Files with Coverage Reduction	New Missed Lines	%
src/commons/fileSystemView/FileSystemViewFileNode.tsx	1	2.78%

Totals
Change from base Build 4508399233:	0.1%
Covered Lines:	4726
Relevant Lines:	12570

---

💛 - Coveralls

[coveralls]

Pull Request Test Coverage Report for Build 4510868611

Warning: This coverage report may be inaccurate.

This pull request's base commit is no longer the HEAD commit of its target branch. This means it includes changes from outside the original pull request, including, potentially, unrelated coverage changes.

• For more information on this, see Tracking coverage changes with pull request builds.
• To avoid this issue with future PRs, see these Recommended CI Configurations.
• For a quick fix, rebase this PR at GitHub. Your next report should be accurate.

Details

• 36 of 39 (92.31%) changed or added relevant lines in 5 files are covered.
• 1 unchanged line in 1 file lost coverage.
• Overall coverage increased (+0.1%) to 35.029%

---

Changes Missing Coverage	Covered Lines	Changed/Added Lines	%
src/commons/fileSystemView/FileSystemViewFileNode.tsx	0	1	0.0%
src/commons/fileSystemView/FileSystemViewDirectoryNode.tsx	0	2	0.0%

Files with Coverage Reduction	New Missed Lines	%
src/commons/fileSystemView/FileSystemViewFileNode.tsx	1	2.78%

Totals
Change from base Build 4508399233:	0.1%
Covered Lines:	4726
Relevant Lines:	12570

---

💛 - Coveralls