Implement classically controlled operations

[theRoughCode]

This PR is a first step at implementing classically controlled operations and is based off of work in this PR. It is part of the Q# visualization tool as described in #158.

In this PR, we:

1. Use the IsConditional flag in the RuntimeMetadata class to check if the given operation is a classically-controlled operation.
2. Implement the same logic as we do for composite operations (i.e. recursively trace nested operations). In this case we would get 2 operations (one for each conditional branch). Upon exit from the recursive tracer, we add them as Children of the outer condition operation.
3. Override the logic for ApplyIfElseR with a custom TracerApplyIfElse.

TODO:

• Implement getting correct classical register
• Use IsConditional flag in visualizer (JS) to determine if the operation is a classically-controlled operation instead of checking children.
• Modify classically-controlled tests in visualizer (JS) to use IsConditional instead of IsControlled.

If this logic makes sense, our next steps are to:

• Override conditional logic for all other variants of ApplyIfElse
• Perform an IRewriteStep to convert if/else statements to ApplyIfElse
• Reduce ApplyIfOne and ApplyIfZero to ApplyIfElse.

[theRoughCode]

Closing this PR in favour of #290.