Regression in template engine path handling

[mattchenderson]

Describe the bug

It looks like #48794 is back, at least with 9.0.305. It seems the changes for resolving that were not pulled over into the newer release: https://github.com/dotnet/sdk/commits/v9.0.305/src/Cli/Microsoft.TemplateEngine.Cli/TemplatePackageCoordinator.cs

Receiving bug reports related to this again for the Azure Functions Core Tools

To Reproduce

(Copied and adapted from original issue)

1. On MacOS using Apple Silicon, install .NET SDK 9.0.305 or later.
2. Create a path that includes an@ character:
   a. mkdir repro@4
3. Put a copy of any templating package into that folder:
   a. dotnet new console
   b. dotnet add package Microsoft.Azure.Functions.Worker.ProjectTemplates -v 4.0.5086 --package-directory ./repro@4
4. Install that package with dotnet new install using the absolute path to it:
   a. dotnet new install ./repro@4/microsoft.azure.functions.worker.projecttemplates/4.0.5086/microsoft.azure.functions.worker.projecttemplates.4.0.5086.nupkg

Exceptions (if any)

See original issue for more complete details, but effectively you end up with ./repro::4/microsoft.azure.functions.worker.projecttemplates/4.0.5086/microsoft.azure.functions.worker.projecttemplates.4.0.5086.nupkg is not supported.`

Further technical details

Clean install of MacOS Tahoe, installing .NET 9 with SDK 9.0.305