Fix loading projects on network drives

[thecrypticace]

Opening a project on a networked drive (e.g. Z:\my-project) would fail because:

• We ask node for the "real" file path which returns a UNC share path (e.g. \\MyShare\some-folder\my-project)
• Improper path normalization
• Errors in enhanced-resolve with UNC paths

Additionally, opening projects on a network share directly (rather than a mapped network drive) would always fail to discover any projects.

I've made some improvements to file path handling such that:

• Loading a project on a network share directly does not outright fail — there are still some problems but they appear to be in enhanced-resolve when resolving relative file paths
• Loading a project on a networked drive no longer uses the UNC path returned by fs.realpath and uses the url that was passed in. This means that symlinks don't get resolved however it should (hopefully) solve most issues when using Intellisense with projects over the network

Fixes #994