don't ngen Microsoft.CodeAnalysis.EditorFeatures.Next.dll

The corresponding VSIX package had the same `<ShortcutPath>` as
Microsoft.CodeAnalysis.EditorFeatures.vsix which caused some problems
during setup ngen because symlinks were replaced.  The .Next.dll only
contains two assembly binding redirect attributes and doesn't need to be
ngen'ed.

* Don't run the IteratorRewriter on BaseMethodWrapperSymbols

* Removing git link

* Removing extra diagnostics check

* Adding execution test

Currently, if you implement an interface with a tuple type as a
substituted type argument that will be accurately represented in source,
but the names will be lost when emitted to metadata.

This PR implements roundtripping for tuples as generic type arguments to
interface implementations in metadata. This is done by adding support
for emitting attributes on interface implementations to Emit. We now
emit the same attribute on interface implementations that we would
on other areas where types may contain nested tuples. Completes the
interface implementation work referenced in #12347.

Support async methods returning Task-like types

[Based on features/async-return with tests ported from that branch.]

[Based on features/async-return with tests ported from that branch.]

Correct the version number and move version to the Targets

Add dependencies between Swixproj

The Swixproj projects encapsulating each Vsix should mention the
dependencies betweeen them similar to the dependencies stated in the
contained Vsixes.

This is causing signing to fail without any messages.  Not on the critical path.

Ensure IBC is running for our official builds.

There will be a corresponding update to the Build Definitions to provide the $(IbcMergePath) value.

Previously, a tuple in a declaration context always required a
TupleElementNamesAttribute to record the names. Now, when the tuple has
no names the compiler will elide the attribute. On loading from
metadata it is assumed that tuples without an attribute have no names.

Fixes #12454

Merge microupdate into dev15-preview-4

Add support for switching on float, double, and decimal.

# Conflicts:
#	src/Workspaces/Core/Portable/SymbolId/SymbolId.cs

Sign Roslyn.VisualStudio.Test.Utilities.dll

This DLL is used by testers and having it unsigned requires some expensive work arounds for them.

Also: restore alphabetical order of other DLLs in this list.

Risk: Very low.

Several of our EE binaries needed to be signed with different certificates than the standard Microsoft one.  Functionality was added to specify the certificate for the binary in question and all remaining references to the AuthenticodeCertificateName property were removed.

Port insertion fixes into dev15-preview-4

Adding back 'Microsoft.VisualStudio.Shell.Interop.SVsLog` interop type.

This adds back `src/Compilers/Core/Portable/Interop/IVsSQM.cs` file and re-adds it to the `src/VisualStudio/Core/Def/ServicesVisualStudio.csproj` project because there is a some VS code with IVT that currently depends on the interop type existing.

The code is a sequence of if-then-else tests using value.Equals(input).
Someday we might do better using divide-and-conquer.

For the most part, this change implements the same encoding
for tuples that we use for dynamic. This means that interface
implementations and generic constraints are not covered, but
base types and type parameters are.

This change also doesn't have full tests for "long" tuples (nested tuple
transformations) or tuple types that can only be constructed in
metadata.

Move last custom MicroBuild step to Roslyn repo

This moves the last custom MicroBuild step into the Roslyn repo.  This now gives us fully control over the binaries produced and their final locations in our source.  No need to coordinate changes to the official build with source changes / branches.

Fix some fast up to date check issues

Merge the typeswitch implementation into master

Merge master into features/typeswitch