Ensure that editor tabs have corresponding files

[ianyong]

Description

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

• When first turning on multiple files mode, program.js is not visible in the sidebar. The file will only appear in the sidebar after typing in some code and then reloading the page.
  

Also centralise the configuration of base paths of each workspace for better cohesion.

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]);

It might be easier to verify this by opening an incognito tab in Chrome. Note that this does not work in Firefox where IndexedDB access is entirely blocked in private browsing mode.

[coveralls]

Pull Request Test Coverage Report for Build 4522526280

• 3 of 18 (16.67%) changed or added relevant lines in 1 file are covered.
• 2 unchanged lines in 2 files lost coverage.
• Overall coverage decreased (-0.03%) to 35.004%

---

Changes Missing Coverage	Covered Lines	Changed/Added Lines	%
src/pages/fileSystem/createInBrowserFileSystem.ts	3	18	16.67%

Files with Coverage Reduction	New Missed Lines	%
src/pages/fileSystem/createInBrowserFileSystem.ts	1	11.11%
src/pages/playground/Playground.tsx	1	2.89%

Totals
Change from base Build 4522515588:	-0.03%
Covered Lines:	4728
Relevant Lines:	12585

---

💛 - Coveralls

[coveralls]

Pull Request Test Coverage Report for Build 4519066109

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

• 3 of 18 (16.67%) changed or added relevant lines in 1 file are covered.
• 2 unchanged lines in 2 files lost coverage.
• Overall coverage decreased (-0.03%) to 34.856%

---

Changes Missing Coverage	Covered Lines	Changed/Added Lines	%
src/pages/fileSystem/createInBrowserFileSystem.ts	3	18	16.67%

Files with Coverage Reduction	New Missed Lines	%
src/pages/fileSystem/createInBrowserFileSystem.ts	1	11.11%
src/pages/playground/Playground.tsx	1	2.89%

Totals
Change from base Build 4508399233:	-0.03%
Covered Lines:	4693
Relevant Lines:	12548

---

💛 - Coveralls