This reduces package restore on Roslyn.sln with all packages already restored from 40 seconds -> 10 seconds.

project.lock.json format has changed since we last updated.

This reverts commit 8f26ffb5.

Turns out we do need a shared DLL project.  A lot of types that need to
be shared between the servers.

Updating System.Reflection.Metadata to 1.1.0-alpha-0015 and System.Collections.Immutable to 1.1.37.0

Revert "Updating System.Reflection.Metadata to 1.1.0-alpha-0015 and System.Collections.Immutable to 1.1.37.0"

This reverts commit d78dbb97.

Updating System.Reflection.Metadata to 1.1.0-alpha-0015 and System.Collections.Immutable to 1.1.37.0

Reverting System.Collections.Immutable back to 1.1.36 until we can upgrade System.Reflection.Metadata simultaneously

Updating Microsoft.DiaSymReader to v1.0.6, Microsoft.DiaSymReader.Native to v1.2.0, and System.Collections.Immutable to v1.1.37

After updating to the latest CoreCLR NuGet packages we no longer need to
be copying binaries from a drop share to run. This change adds a csc.sh
and a vbc.sh so we can run on the CoreRun host on Linux like we do on
Windows. The change also eliminates some cruft from the cibuild like the
semaphore restore.

Adds a new type, CoreClrAnalyzerAssemblyLoader, that is responsible
for finding and loading analyzer assemblies on CoreCLR. This is used
in the CscCore and VbcCore CoreCLR-targeting projects.

Some of the references were outdated and some of the NuGet packages
were incorrectly authored. With the new references we don't need to
do any extra work to copy over the CoreCLR runtime -- it's copied as
a reference by NuGet 3 without any extra work.

Rogjt mpw we build a boostrap version of csc and vbc and bootstrap
with those running on Mono. This commit switches us to build a CoreCLR
compatible csc and then running the boostrap on CoreCLR

Right now the full set of Linux CoreCLR runtime assemblies is not
available on NuGet, so we substitute with some assemblies we stash in
our NuGet ZIP package.