Authored by: Steve Pfister, and Mitchell Hwang

.. on helix.

- Essentially, we are building the test assembly on the build machine
- then we package that up, with bits required to be able to
  "wasm-app-ify" the assembly on Helix
  - We already do parts of it for wasm build tests, so make use of that

  - Also, fix bugs in recreating the test project on helix, eg. files to
    be included in the VFS.

- Since, the AOT tests will be run with `EnableAggressiveTrimming=true`,
  some issues can be due to the trimming itself.
  - to help isolate such issues, we want to be able to build in the
    *same* way (on helix), with just EAT
  - so, this commit helps facilitate that

…r commit

```
/_/src/libraries/System.Linq.Expressions/tests/Member/MemberAccessTests.cs(503,82): Trim analysis error IL2103: System.Linq.Expressions.Tests.MemberAccessTests.<>c.<Property_GenericPropertyAccessor_ThrowsArgumentException>b__38_0(): Value passed to the '#1' parameter of method 'System.Linq.Expressions.MemberExpression System.Linq.Expressions.Expression::Property(System.Linq.Expressions.Expression,System.Reflection.MethodInfo)' cannot be statically determined as a property accessor. [/__w/1/s/src/libraries/System.Linq.Expressions/tests/System.Linq.Expressions.Tests.csproj]
/_/src/libraries/System.Linq.Expressions/tests/Member/MemberAccessTests.cs(504,82): Trim analysis error IL2103: System.Linq.Expressions.Tests.MemberAccessTests.<>c.<Property_GenericPropertyAccessor_ThrowsArgumentException>b__38_1(): Value passed to the '#1' parameter of method 'System.Linq.Expressions.MemberExpression System.Linq.Expressions.Expression::Property(System.Linq.Expressions.Expression,System.Reflection.MethodInfo)' cannot be statically determined as a property accessor. [/__w/1/s/src/libraries/System.Linq.Expressions/tests/System.Linq.Expressions.Tests.csproj]
/_/src/libraries/System.Linq.Expressions/tests/Member/MemberAccessTests.cs(459,74): Trim analysis error IL2103: System.Linq.Expressions.Tests.MemberAccessTests.<>c.<Property_InstanceProperty_NullExpression_ThrowsArgumentException>b__33_3(): Value passed to the '#1' parameter of method 'System.Linq.Expressions.MemberExpression System.Linq.Expressions.Expression::Property(System.Linq.Expressions.Expression,System.Reflection.MethodInfo)' cannot be statically determined as a property accessor. [/__w/1/s/src/libraries/System.Linq.Expressions/tests/System.Linq.Expressions.Tests.csproj]
/_/src/libraries/System.Linq.Expressions/tests/Member/MemberAccessTests.cs(511,82): Trim analysis error IL2103: System.Linq.Expressions.Tests.MemberAccessTests.<>c.<Property_PropertyAccessorNotFromProperty_ThrowsArgumentException>b__39_0(): Value passed to the '#1' parameter of method 'System.Linq.Expressions.MemberExpression System.Linq.Expressions.Expression::Property(System.Linq.Expressions.Expression,System.Reflection.MethodInfo)' cannot be statically determined as a property accessor. [/__w/1/s/src/libraries/System.Linq.Expressions/tests/System.Linq.Expressions.Tests.csproj]
/_/src/libraries/System.Linq.Expressions/tests/Member/MemberAccessTests.cs(448,76): Trim analysis error IL2103: System.Linq.Expressions.Tests.MemberAccessTests.<>c__DisplayClass32_0.<Property_StaticProperty_NonNullExpression_ThrowsArgumentException>b__2(): Value passed to the '#1' parameter of method 'System.Linq.Expressions.MemberExpression System.Linq.Expressions.Expression::Property(System.Linq.Expressions.Expression,System.Reflection.MethodInfo)' cannot be statically determined as a property accessor. [/__w/1/s/src/libraries/System.Linq.Expressions/tests/System.Linq.Expressions.Tests.csproj]
/_/src/libraries/System.Linq.Expressions/tests/Member/MemberAccessTests.cs(472,76): Trim analysis error IL2103: System.Linq.Expressions.Tests.MemberAccessTests.<>c__DisplayClass34_0.<Property_ExpressionNotReadable_ThrowsArgumentException>b__3(): Value passed to the '#1' parameter of method 'System.Linq.Expressions.MemberExpression System.Linq.Expressions.Expression::Property(System.Linq.Expressions.Expression,System.Reflection.MethodInfo)' cannot be statically determined as a property accessor. [/__w/1/s/src/libraries/System.Linq.Expressions/tests/System.Linq.Expressions.Tests.csproj]
/_/src/libraries/System.Linq.Expressions/tests/Member/MemberAccessTests.cs(482,74): Trim analysis error IL2103: System.Linq.Expressions.Tests.MemberAccessTests.<>c__DisplayClass35_0.<Property_ExpressionNotTypeOfDeclaringType_ThrowsArgumentException>b__2(): Value passed to the '#1' parameter of method 'System.Linq.Expressions.MemberExpression System.Linq.Expressions.Expression::Property(System.Linq.Expressions.Expression,System.Reflection.MethodInfo)' cannot be statically determined as a property accessor. [/__w/1/s/src/libraries/System.Linq.Expressions/tests/System.Linq.Expressions.Tests.csproj]
```