1. Fix test issues
2. Remove IHasDynamicArgumentsExpression interface and move the Arguments property from it to individual IDynamicXXXExpression nodes.
3. Adjust the extension methods for GetArgumentName and GetArgumentRefKind accordingly.

In preparation for a merge of features/ioperation to master, we have decided to internalize all the IOperation APIs which are either not tested or not reviewed by the design team.
This includes the following APIs with bugs tracking reviewing/adding tests for them: IArrayElementReferenceExpression(https://github.com/dotnet/roslyn/issues/22006), IAwaitExpression(https://github.com/dotnet/roslyn/issues/22007), ICatchClause(https://github.com/dotnet/roslyn/issues/22008), IEndStatement(https://github.com/dotnet/roslyn/issues/22004), IPlaceholderExpression(https://github.com/dotnet/roslyn/issues/21294), ISizeOfExpression(https://github.com/dotnet/roslyn/issues/21296), IStopStatement(https://github.com/dotnet/roslyn/issues/21297), ITryStatement(https://github.com/dotnet/roslyn/issues/22008), ITypeOfExpression(https://github.com/dotnet/roslyn/issues/22003), IWithStatement(https://github.com/dotnet/roslyn/issues/22005)

This change also includes a simple API rename: IMethodBindingExpression renamed to IMethodReferenceExpression(https://github.com/dotnet/roslyn/issues/21289).

1) Use IDynamicInvocationExpression for VB late bound invocation and C# dynamic invocation.
2) Use IDynamicIndexerAccessExpression for C# dynamic indexer access; not used in VB.
3) Remove IDynamicObjectCreationExpression.MemberName property.
4) Add extension methods on IHasDynamicArgumentExpression to get optional argument name and ref kind for an argument at a given index.

1. Add Locals property to ILoopStatement
2. Remove IterationVariable from foreach loops and VB ForTo loops.
3. Add InvalidCondition to Do loops for VB error cases.
4. Rename property AddLoopBottomExpressionList to NextVariables
5. Add relevant unit tests
6. Remove ISyntheticLocalReferenceExpression and SyntheticLocalKind

Fixes #8882

1. Flatten the loop statement hierarchy to only derive from ILoopStatement
2. Separate out do loops and while loops
3. Separate out the C# and VB for loops due to different semantics and syntax.

Fixes #21282

Fixes #20114 and #20122

1. Add IsChecked flag for IIncrementExpression and ICompoundAssignmentExpression
2. Add back VB specific binary operator kinds
3. Add more unit tests and fix baselines of existing tests

Updated VB to handle BoundUserConversion correctly, get conversionkind directly from the BoundNodes.