Merge master to features/ioperation

Merge `private protected` feature into master for C# 7.2 and VB 15.6.

Address feedback from Aleksey and generate a dynamic member reference expression for a bound method group that is a child of dynamic invocation

Merge master into privateProtected branch

Fixed Inline Temporary Variable refactoring

Updating some nuspec to list the correct framework requirements and dependencies.

Fix IArgument.InConversion/OutConversion

Merge master to features/ioperation

Merge master to features/ioperation

Delete .Next projects

* Remove context (enclosing type name) from C# parser.
* Add a test demonstrating that unicode escapes are significant to determining if a method is a ctor.
This is a prerequisite to #367

Merge master into privateProtected

Fix up .gitattributes to clone .sh files with LF

This transfers all the VSIX contents of VisualStudioSetup.Next
back to VisualStudioSetup, making VisualStudioSetup a Dev15 VSIX again.

We don't need the split anymore now that we're only supporting Dev15.

Unfortunately this required the introduction of a NuGet package that
has a namespace "Workspace" to our VS project, which meant I had to
disambiguate Workspace wherever it's used in that layer. I considered
doing an extern alias instead to disambiguate, but applying that to a
ProjectReference isn't supported. That's tracked by NuGet/Home#4989.

This lived in EditorFeatures.Next since it depended on Dev15 features,
but EditorFeatures is now Dev15 only so we can move this.

These helpers allowed us to do lightup between Dev14 and Dev15 for some
features. We no longer support Dev14, so that is unnecessary.

Previously, we supported a light-up ability where we would use the
appropriate Navigate To APIs for Dev14 or Dev15 depending upon which
version of Visual Studio we were targeting. We no longer support such
a configuration, so we can flatten all the code and indirection back
down.

Previously, we supported a light-up ability where we would use the
appropriate completion APIs for Dev14 or Dev15 depending upon which
version of Visual Studio we were targeting. We no longer support such
a configuration, so we can flatten all the code and indirection back
down.

Fix completion crash in tuple in alias

Stop swallowing JTF exceptions

1. Fix test issues
2. Remove IHasDynamicArgumentsExpression interface and move the Arguments property from it to individual IDynamicXXXExpression nodes.
3. Adjust the extension methods for GetArgumentName and GetArgumentRefKind accordingly.

Merge dev15.4.x to master

Fix issue with merging parameters

We were not generating a cached completion item rule for a non-preselected item in a tuple context that was also an alias context
Fixes https://github.com/dotnet/roslyn/issues/22002