Properties: Support searching for Boolean/Checkbox state like [completed:true]

Thank you for posting this! I was not certain whether this was intended behavior or not.

I do think it would make sense to clarify in the help docs that this search format is not currently implemented for numbers and boolean values, since the examples given in the docs appear to indicate that the [property:value] search format works for properties and values in general, and right now it does not.

By the way, I am very much enjoying the properties feature, it came out just in time for me to add new functionality to my DnD campaign notes! Especially combined with templates that duplicate sets of properties, it really helps me organize fiddly things like spells.