Resolving InstallationId writes to disk by default

[bitsandfoxes]

Problem

Writing to disk on restricted platforms - i.e. Nintento Switch - causes the game to crash: getsentry/sentry-unity#1804

What's happening

We're fetching the installationId lazily

sentry-dotnet/src/Sentry/SentryOptions.cs

Line 1184 in 9ad2caa

_lazyInstallationId = new(() => new InstallationIdHelper(this).TryGetInstallationId());

and during event enrichment that installationId gets resolved

sentry-dotnet/src/Sentry/Internal/Enricher.cs

Line 83 in 9ad2caa

eventLike.User.Id ??= _options.InstallationId;

and this causes the InstallationIdHelper to attempt to create a persistent installationId on disk

sentry-dotnet/src/Sentry/Internal/InstallationIdHelper.cs

Lines 30 to 33 in 9ad2caa

	var id =
	TryGetPersistentInstallationId() ??
	TryGetHardwareInstallationId() ??
	GetMachineNameInstallationId();

sentry-dotnet/src/Sentry/Internal/InstallationIdHelper.cs

Lines 48 to 56 in 9ad2caa

	private string? TryGetPersistentInstallationId()
	{
	try
	{
	var rootPath = options.CacheDirectoryPath ??
	Environment.GetFolderPath(Environment.SpecialFolder.LocalApplicationData);
	var directoryPath = Path.Combine(rootPath, "Sentry", options.Dsn!.GetHashString());
	Directory.CreateDirectory(directoryPath);

Solutions

1. Change the accessor for InstallationId from internal to public. That way the Unity SDK can overwrite the lazy initialization during options construction. (Hacky)
   

   sentry-dotnet/src/Sentry/SentryOptions.cs

   Line 45 in 9ad2caa

   internal string? InstallationId => _lazyInstallationId.Value;

2. Add controls over writing to disk. That could be a new option. Or we reuse CacheDirectoryPath. With the CacheDirectoryPath set to null we skip all operations writing to disk. We've already got FileSystem in place.
   

   sentry-dotnet/src/Sentry/Internal/FileSystem.cs

   Line 19 in 9ad2caa

   public void CreateDirectory(string path) => Directory.CreateDirectory(path);

   
   We could replace all instances of the SDK directly calling Directory.Create for File.Write going through FileSystem and make that adhere to the options.

[bitsandfoxes]

Going with solution 2. It's been like that for some time so there's no need to hack something together. Let's introduce a new options i.e. DisableFileWrite and route all writing to disk through our FileSystem.
Todo: Make sure reading from disk actually works on those restricted platforms.