[FEATURE REQUEST] add "ifelse" Jinja function as found in CFEngine

[nicholasmhughes]

Describe the solution you'd like
Some users transitioning over from CFEngine have expressed a desire to have functionality similar to the ifelse function found in CFEngine.

Describe alternatives you've considered
The concept is very similar to match.filter_by, but necessitates adding all items into a dictionary in order to perform the evaluation.

Additional context
Providing this functionality should be pretty low effort considering it could be a wrapper that passes to match.filter_by.

Please Note
If this feature request would be considered a substantial change or addition, this should go through a SEP process here https://github.com/saltstack/salt-enhancement-proposals, instead of a feature request.