Create Control Flow Graph regions to designate life-time of flow captures in a Control Flow Graph. A region should start as soon as a capture is needed to accurately represent the order of evaluation within operations involving control of flow. However, it should not start too soon. For example, if there is a branch that represents an execution path that bypasses the use of a capture completely, that branch should not be included into the region for the capture. Also, the region should end as soon as the last operation referencing the capture is reached.

Also add SemanticModel.GetControlFlowGraph API overloads for these initializer operations.

Fixes #22581

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

This reverts commit 27dc60f5.

Ensure complete information is consistently captured in a bound tree for an explicit C# conversion implicitly applied by compiler. (#22703)

Fixes #7299. Fixes #19878

* Adding cobyrc file for testing

* Adding isImplicit info to ioperation tests

* Adding Language name to the test dumper

* Formatting change to test dumper

* Removing cobyrc file

* Fixing more tests

* Resolving conflicts

* Moving the language to assert check

* Resolving conflicts

* Reacting to merge conflict

* Tagging VB/C# Ioperation tests

* Fix the Wrong Tagging

* Changing the dumper to get of calling base.Visit when not needed

* Getting rid of cobyrc file

* Adding copyright header

* fixing merge conflict

* Change the IOperation unit test dump format for child nodes

* fixing the newly merged tests.

There are couple of changes here:
1. API change: `ImmutableArray<ISymbolInitializer> MemberInitializers` is changed to `ImmutableArray<IOperation> Initializers`.
2. Implementation changes:
   1. Instead of returning the member initializers as synthesized ISymbolInitializer nodes, we now return member intializers as IAssignmentExpression nodes. This ensures completeness of IOperation tree.
   2. Now we also return the collection intializer expressions within an object creation expression.

Fixes #18115

There are 2 bugs still affecting this area:
1. #18781: IOperation API shape for collection initializer expressions
2. #19276: Missing Field/Property reference expression nodes in object creation initializer node

Since we will try to repalce the logic with existing rewriter, it makes more sense to
minimize the code change here. Also removed the corresponding tests, will fix and add
them back after the implementation is finalized. As result, the contract for
IHasArgumentsExpression.ArgumentsInEvaluationOrder in C# is broken.

Enhance IOperation dumper to dump snippet of syntax and child property names. I have also fixed the existing IOperation tests.

These APIs will be used in autogenerated unit test for Operation tree verification.

Fixes #17595