add threats by element for STRIDE/LINDDUN/PLOT4ai/CIA/DIE

Reinstating automated threat suggestion per element was a feature in the threat dragon threat model designing system. Hence, upon migration to Vue.JS framework, not all features where migrated as that would take much effort to be completed. Yet, the project is continuously reinstating old features with new ones to make threat dragon an even better threat model designing system. This specific project is about suggesting threat type automatically for an element upon creation when drawing a threat model. My solution is about tracking our current existing threats for this element. and upon creating a new threat, the algorithm would check the existing threats and with the map it has for matching suggestions, it would pick the threat type suggestion for the next created threat.