Language server crashes handling file paths with Turkish I

[minestarks]

Repro: Open a file in VS Code with İ in the path, and an import statement

mkdir İ
cd İ
echo import { foo } from "bar" > foo.js
code .

Language service dies.

Impacts both VS and VS Code on both Windows and Mac OS.

In VS Code:

    No Project.

    Error: No Project.
        at Object.ThrowNoProject (%localappdata%\Programs\Microsoft VS Code\resources\app\extensions\node_modules\typescript\lib\tsserver.js:128093:23)
        at ProjectService.doEnsureDefaultProjectForFile (%localappdata%\Programs\Microsoft VS Code\resources\app\extensions\node_modules\typescript\lib\tsserver.js:131030:131)
        at ProjectService.ensureDefaultProjectForFile (%localappdata%\Programs\Microsoft VS Code\resources\app\extensions\node_modules\typescript\lib\tsserver.js:131025:75)
        at IOSession.Session.getFileAndProjectWorker (%localappdata%\Programs\Microsoft VS Code\resources\app\extensions\node_modules\typescript\lib\tsserver.js:134578:87)
        at IOSession.Session.getFileAndProject (%localappdata%\Programs\Microsoft VS Code\resources\app\extensions\node_modules\typescript\lib\tsserver.js:134561:29)
        at IOSession.Session.getApplicableRefactors (%localappdata%\Programs\Microsoft VS Code\resources\app\extensions\node_modules\typescript\lib\tsserver.js:135011:31)
        at Session.handlers.ts.createMapFromTemplate._a.<computed> (%localappdata%\Programs\Microsoft VS Code\resources\app\extensions\node_modules\typescript\lib\tsserver.js:133868:61)
        at c:\Users\mineyalc\AppData\Local\Programs\Microsoft VS Code\resources\app\extensions\node_modules\typescript\lib\tsserver.js:135256:88
        at IOSession.Session.executeWithRequestId (%localappdata%\Programs\Microsoft VS Code\resources\app\extensions\node_modules\typescript\lib\tsserver.js:135247:28)
        at IOSession.Session.executeCommand (%localappdata%\Programs\Microsoft VS Code\resources\app\extensions\node_modules\typescript\lib\tsserver.js:135256:33)
        at IOSession.Session.onMessage (%localappdata%\Programs\Microsoft VS Code\resources\app\extensions\node_modules\typescript\lib\tsserver.js:135279:35)
        at Interface.<anonymous> (%localappdata%\Programs\Microsoft VS Code\resources\app\extensions\node_modules\typescript\lib\tsserver.js:136594:27)
        at Interface.emit (events.js:200:13)
        at Interface._onLine (readline.js:314:10)
        at Interface._normalWrite (readline.js:459:12)
        at Socket.ondata (readline.js:170:10)
        at Socket.emit (events.js:200:13)
        at addChunk (_stream_readable.js:294:12)
        at readableAddChunk (_stream_readable.js:275:11)
        at Socket.Readable.push (_stream_readable.js:210:10)
        at Pipe.onStreamRead (internal/stream_base_commons.js:166:17)

In VS (ADO bug)

getDirectoryToWatchFailedLookupLocation(tsserver.js:98851:26)
watchFailedLookupLocationOfResolution(tsserver.js:98919:31)
suppressed_frame()
watchFailedLookupLocationOfNonRelativeModuleResolutions(tsserver.js:98949:25)
suppressed_frame()
clearPerDirectoryResolutions(tsserver.js:98717:50)
Object.finishCachingPerDirectoryResolution(tsserver.js:98723:13)
ExternalProject.Project.updateGraphWorker(tsserver.js:135025:38)
ExternalProject.Project.updateGraph(tsserver.js:134966:42)
ExternalProject.updateGraph(tsserver.js:135963:59)
ProjectService.openExternalProject(tsserver.js:138655:29)
ProjectService.openExternalProjects(tsserver.js:138406:26)
Session.handlers.ts.createMapFromTemplate._a.(tsserver.js:139167:46)
unknown_function(tsserver.js:140854:88)
IOSession.Session.executeWithRequestId(tsserver.js:140845:28)
IOSession.Session.executeCommand(tsserver.js:140854:33)
IOSession.Session.onMessage(tsserver.js:140877:35)
Interface.(tsserver.js:142192:27)
suppressed_frame()
suppressed_frame()
suppressed_frame()
suppressed_frame()
suppressed_frame()
suppressed_frame()
suppressed_frame()
suppressed_frame()

The root cause is that the behavior of tolower() does not always match file system casing rules in case-insensitive file systems. To my knowledge, there is no API in Node.js or Windows that lets you access the actual casing rules. Furthermore, our check as to whether the file system is case-sensitive or not is rather naive and ignores possibilities like case-sensitive directories on Windows. Here are some best practices from Node.

While the true fix would be to always preserve casing for file paths in the language service, in practice special-casing "Turkish İ" will fix pretty much all occurrences of this issue.

[minestarks]

May be a possible root cause of #33186

[minestarks]

Related: #31819