Add refactoring to convert foreach loop into linq invocations (Select…

Fixes #29416 

Instructions can be found in the README file under src/Tools/CompilerBenchmarks.

Update unix contributing docs

Add refactoring to convert foreach loop into linq invocations (Select, SelectMany and Where invocations)

Adds one of the refactorings mentioned in #8953

```
//
// INPUT:
//   foreach (var n1 in c1)
//      foreach (var n2 in c2)
//          if (n1 > n2)
//              yield return n1 + n2;
//
// OUTPUT:
//   c1.SelectMany(n1 => c2.Where(n2 => n1 > n2).Select(n2 => n1 + n2))
//
```

Update 'use block body' to be better understand async methods.

Added Newtonsoft.Json to exclusion list

Updated the docs based on my experiences getting the emit tests running
on Linux.

Don't fire IDE0009 incorrectly in List initializers

Support parameter initialization refactorings when teh parameter name is selected.

Add explicit case clause(s) for all the bound nodes for which right now we fall back to creating operation None node. Throw from default case.

Fixes https://github.com/dotnet/arcade/issues/458

Fix casing for System.Xml.dll

Remove spurious "cast is redundant" when accessing hidden member

Fix issue preventing introduce-variable working on an expression being indexed into

Find-Refs on an accessor should only produce results for that accessor.

Merge dev15.9.x to master

Add GetCorrespondingLoop() (and Switch) branch operation extensions

This fix allows the rsp file to be used on case sensitive file systems like Linux.

Migrate to Microsoft.VisualStudio.Threading

There's a problem on MacOS where the pipe name may be too long to
use as a Unix domain socket. Unfortunately, there's no way in the
version of CoreFX that we reference to override the path name
used for the named pipe. If the path is too long then the compiler
server spins infinitely trying to connect to a path.

Since we can't use our own path, the best we can do right now is
abort compiler server usage if the path would be too long. This
commit adds a check on Unix machines running on CoreCLR to
detect when the constructed path will be too long, and bail out
if this is the case.

The AbstractSpeculationAnalyzer would check whether casting symbols
used in Invocable expressions would break semantics. However it was not
considering all MemberAccess to be potentially invokable. This Changes
the IsInvokable check to consider all MemberAccess expressions.

This fixes #28412.