Write documentation for property reactivity behavior details

[tkobayas]

Probably it's good to have one section to focus on property reactivity behavior with some more details.

• Existing basic explanation
• Class reactive (= react to all properties) when properties in constraint cannot be analyzed
• A method call reacts to properties which are method arguments https://docs.drools.org/7.73.0.Final/drools-docs/html_single/#better-property-reactivity

[tkobayas]

Note:
DROOLS-3849 (no mask -> allSetBitMask when properties in constraint cannot be analyzed)
-> since 7.21.0.Final

DROOLS-5677 (if firstProp is not a property nor a method call, allSetBitMask : e.g. Object1( !Objects.isNull(field1) ))
-> since 7.45.0.Final
-> check if this should be removed : #6092

BAPL-1773 (reactive to method call arguments)
-> since 7.46.0.Final