Json escape should use two equality checks instead of HashMap lookup

We escape Json using a HashMap lookup for two characters. We should instead just two equality checks instead of a relatively expensive map lookup for every character in the String.

https://github.com/infinispan/infinispan/blob/ccf0f526013e58fbc44a88f5da1d75c2c0320e41/commons/all/src/main/java/org/infinispan/commons/dataconversion/internal/Json.java#L2810