Ensure there's a separator between nuget cache and storage tools paths in Common.Netcore.Dependencies.targets

[anton-evseev]

Description

If you have custom NuGet cache path defined in env variable NUGET_PACKAGES that doesn't end with \ the path in StorageToolsPath would be incorrect and result in an error like this:

CSC : error CS2001: Source file 'C:\Users\linxyang.nugetmicrosoft.azure.powershell.storage\1.3.13-preview\tools\Adapters\ARM.Storage.6\ARMStorageProvider.cs' could not be found. [C:\git\azure-powershell\src\Storage\Storage.Management\Storage.Management.csproj] [C:\git\azure-powershell\build.proj]

Notice \.nugetmicrosoft.azure.powershell.storage\

This PR would fix that.

Checklist

• I have read the Submitting Changes section of CONTRIBUTING.md
• The title of the PR is clear and informative
• The appropriate ChangeLog.md file(s) has been updated:
  • For any service, the ChangeLog.md file can be found at src/{{SERVICE}}/{{SERVICE}}/ChangeLog.md
  • A snippet outlining the change(s) made in the PR should be written under the ## Upcoming Release header -- no new version header should be added
• The PR does not introduce breaking changes
• If applicable, the changes made in the PR have proper test coverage
• For public API changes to cmdlets:
  • a cmdlet design review was approved for the changes in this repository (Microsoft internal only)
  • the markdown help files have been regenerated using the commands listed here