Support filter comparison of boolean values

[glyn]

• https://cburgmer.github.io/json-path-comparison/results/filter_expression_with_equals_false.html
• https://cburgmer.github.io/json-path-comparison/results/filter_expression_with_equals_true.html

[glyn]

Boolean values are unquoted true and false. Quoted values are strings and should not be treated as booleans.