Eliminate dependency on native host for shell

PSRP will of course still require it, but now the managed host sets up
the assembly load context, meaning we can depend on the emitted binary
from dotnet-cli.

debug.sh

@@ -1,2 +1 @@
-export CORE_ROOT=$(pwd)/bin
-lldb-3.6 -o "plugin load ./bin/libsosplugin.so" -- ./powershell $@
+lldb-3.6 -o "plugin load ./bin/libsosplugin.so" -- ./bin/Microsoft.PowerShell.Linux.Host $@

pester.sh

@@ -1,5 +1,4 @@
-export CORE_ROOT=$(pwd)/bin
-./powershell -c "Invoke-Pester src/pester-tests/$1 -OutputFile pester-tests.xml -OutputFormat NUnitXml"
+./bin/Microsoft.PowerShell.Linux.Host -c "Invoke-Pester src/pester-tests/$1 -OutputFile pester-tests.xml -OutputFormat NUnitXml"
 # XML files are not executable
 chmod -x pester-tests.xml
 # Fix tty due to possible bug in .NET

powershell

@@ -1 +0,0 @@
-src/monad-native/host/powershell

run.sh

@@ -1,4 +1,3 @@
-export CORE_ROOT=$(pwd)/bin
-./powershell $@
+./bin/Microsoft.PowerShell.Linux.Host $@
 # Fix tty due to possible bug in .NET
 stty echo

src/Microsoft.PowerShell.Linux.Host/main.cs

@@ -18,6 +18,12 @@ namespace Microsoft.PowerShell.Linux.Host
         /// </summary>
         public static void Main(string[] args)
         {
+            // Setup the Assembly Load Context, which Core PowerShell uses to
+            // analyze the libraries for types, functions, cmdlets, etc. and
+            // provide the ability to load assemblies by file path. Doing this
+            // here eliminates the need for a custom native host.
+            PowerShellAssemblyLoadContextInitializer.SetPowerShellAssemblyLoadContext(AppContext.BaseDirectory);
+
             // Custom argument parsing
             string initialScript = null;
             if (args.Length > 0)