VB EnC: when lowering conditional branches produce a pattern that allows the debugger to perform function remapping

Add AssemblyRefs and TypeRefs to assemblies and types referenced by imports, even if they are not referenced otherwise

Now that the comment formatting issue is fixed in the Formatter type, we can run the formatter on the remainder of the VB code base.

closes #1424

Categorize synthesized query lambdas
Make sure SynthesizedLambdaSymbol and BoundQeuryLambda has the same syntax

VB compiler does not correctly place sequence points in let clause. As a result the debugger does not hit a sequence point set to let clause. Before this fix, we have the following in PDB:

	<sequencePoints>
		<entry offset="0x0" hidden="true" document="0"/>
		<entry offset="0x1" startLine="8" startColumn="25" endLine="8" endColumn="30" document="0"/>
	</sequencePoints>

After having this fix, we have as in Dev12:

            <sequencePoints>
                <entry offset="0x0" startLine="8" startColumn="25" endLine="8" endColumn="30" document="0"/>
            </sequencePoints>

- Resolve Code review feedback

The compiler emits catch-all handler to all async methods. In case of async void methods we also emit the offset of the catch handler to PDB, so that the debugger can pretend that exceptions thrown by the async method are unhandled. Otherwise they are lost. Currently the compiler emits wrong offset, so the debugger is completely confused and displays "no source location" when such exception occurs.

     The fix is to remove a synthesized "nop" instruction that was incorrectly used to track the catch handler IL offset. Instead mark the synthesized BoundCatchHandler node by a flag and create the IL marker in the CodeGen when emitting instructions for such bound node.

     Affects both C# and VB.

     Fixes bug 1114809. (changeset 1405564)

Changes the 4.0+ lock statement IL pattern to improve debugging experience and to match VB compiler. Previously “restarting” the lock by dragging IP to the lock() statement header didn’t reset “lockTaken” flag and Monitor.Enter threw an exception.
Fixes bug 767299.
 (changeset 1403711)