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

looks like I broke it when I did refactoring on KeepAliveSession by giving in wrong callback object.

fix https://github.com/dotnet/roslyn/issues/22806

opened this for adding unit test - https://github.com/dotnet/roslyn/issues/22808

currently we don't have test around ISymbolSearchService.

Closes #7582.

1. Ensure correct syntax nodes and implicit state are used for IArgument nodes matching OmittedArgumentSyntax. Fixes #22486.
2. Ensure correct argument kind is associated with synthesized arguments within query expressions. Fixes #22066.
3. Ensure the invariant that “each syntax node has at most one corresponding explicit IOperation node” is met for all test scenarios we have at the moment. In order to achieve this the following changes are made:
-mark some synthesized bound nodes as compiler generated.
-for assignment statements, ensure that ISimpleAssignmentExpression and ICompoundAssignmentExpression nodes are marked as Implicit because they are sharing syntax node with containing IExpressionStatement and VB doesn’t have a concept of an assignment expression.
-for throw statements, ensure that IThrowExpression node is marked as Implicit because it is sharing syntax node with containing IExpressionStatement and VB doesn’t have a concept of a throw expression.
-for Add/RemoveHandler statements, ensure that IEventAssignmentExpression node is marked as Implicit because it is sharing syntax node with containing IExpressionStatement and VB doesn’t have a concept of an event assignment expression.
-ensure that receivers for IPropertyReferenceExpression representing references to query range variables are marked as implicit.
-ensure that IPropertyReferenceExpression and IParameterReferenceExpression nodes representing references to query range variables are associated with correct syntax nodes.
-ensure that return statements and blocks in query lambdas are marked as implicit.
-for IInterpolatedStringText node, ensure the underlying ILiteralExpression is marked as implicit because it is sharing syntax node with its parent.

Ensire that IOperation nodes representing param arrays and default values are properly marked as implicit. (#22758)

Fixes #21451.

Fixes https://devdiv.visualstudio.com/DevDiv/_workitems?id=481125

* Update PDB converter to 1.1.0-beta1-62221-01

* Enable more conversion tests

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

Fixes a case where large projects repeatedly deserialized syntax trees,
resulting in severe UI delays while typing.

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

The use of Assert.True() is confusing as you end up with:

Expected: [set]
Actual: [another set]
Expected: True
Actual: False

This dispenses of the second expected/actual.

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.

Before this, if we couldn't find the project we'd throw exceptions
and possibly crash or do something bad.

Holding onto Project directly meant the snapshot would be leaked. We
should only hold onto the SymbolKey so we can resolve it later.

* Closes #18171

* ReadOnly Tuple Structs

* Closes #18172