Do not evaluate untaken if and switch branches

[mi25iw]

Resolves #713

The samples for json-e indicate that one can check for an value in an if statement and attempt to use it in the 'then' block.

This change delays evaluating the 'then' and 'else' blocks until they are needed, and a similar change is applied to the 'switch' statement.

The change for IfThenElseOperator is fairly straightforward. The SwitchOperator one was as well, although it does change the order from:

1. Evaluate parameter dictionary (JsonE.Evaluate(parameter, context)!.AsObject();)
2. Check truthiness
3. Copy value

to:

1. Iterate over parameter dictionary (keys have not yet went to JsonE.Evaluate! Not sure if this is important. I saw one code path that looked like it might unescape keys or impact it another way. Please review carefully.)
2. Check truthiness
3. Evaluate value (and still copy it since the original code did, I'm new to the codebase so that might not be necessary).

It passed all the tests still, but I am not super comfortable that I changed the order above. I'm hoping you know (or have any easy way to check) if that's problematic.

[gregsdennis]

Nice! I'll pull this into an update branch to do version and release note stuff. It'll publish when that merges.

[gregsdennis]

The copying is due to JsonNode only being allowed to have a single parent. It's generally necessary because we're likely pulling nodes from other JSON structures, but I don't like it. I could do some inspection to determine whether the specific situation calls for it, but... meh.

[mi25iw]

Makes sense. Thanks for the quick response (and for the libraries in general)!