Fixes #27627

This was missed as part of #22774 for #22719.
Fixes #22719

Refactor ISingle and IMulti to IVariableDeclarator and IVariableDeclaration, to match syntax terms and be less confusing.

Refactored BoundLocalDeclaration to have separate initializers for Array bounds and the standard declaration.

Address more feedback from design meeting and expose IOperation.IsExpression and IOperation.IsStatement properties

Microsoft.CodeAnalysis.Semantics renamed to Microsoft.CodeAnalysis.Operations

1. Rename -Expression and -Statement nodes to -Operation
2. Ensure all IOperation interfaces are suffixed with Operation
3. Rename all OperationKinds to match the corresponding IOperation interfaces without the prefix I and suffix Operation. Also fixed the operation ranges to be all contigous range.
4. Rename all the OperationVisitor methods to also match the corresponding IOperation interfaces without the prefix I and suffix Operation.
5. Merge the following interfaces which were semantically same, but syntactically different:
   1. IInvalidExpression and IInvalidStatement merged to IInvalidOperation
   2. IIfStatement and IConditionalExpression merged to IConditionalOperation
6. Update doc comments for all IOperation APIs to have 2 sections:
   1. Summary section which cites pure semantics of the API without any mention of the language, expression/statement, current usage/implementation, etc.
   2. Current usage para which cites how these APIs are used in current C# and VB implementation of these interfaces.

Fixes #22692

See [OperationExtensions.GetRootOperation](http://source.roslyn.io/#Microsoft.CodeAnalysis/Operations/OperationExtensions.cs,91) API.
This API existed from original IOperation prototype, has never been implemented and always returns null.

Fixes #22691

Addresses https://github.com/dotnet/roslyn/issues/22124.

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.

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.

expose Root from SemanticModel
shared same test methods between C# and VB
removed DEBUG region and used foreach
added clone test for c# and vb
use ArrayBuild as Stack

IsInvalid -> HasDiagnostics
removed HasChildren interface and merged it to IOperation

Refactored IVariableDeclaration to IVariableDeclarationGroup, which allows for multiple declared symbols as part of a single declaration.

With the intention to add them back after the interface and implementation of IHasArgumentsExpression is finalized.