Add support for BPMN data objects

[matthiaslehnertum]

This change adds suport for BPMN data objects.

Checklist

• [x] I documented the TypeScript code using JSDoc style.
• [x] I added multiple screenshots/screencasts of my UI changes
• [x] I translated all the newly inserted strings into German and English

Motivation and Context

Data objects are the most important artifact of BPMN diagrams and therefore need to be supported.

Description

This change adds data objects to BPMN diagrams.

Steps for Testing

1. Create a new BPMN diagram
2. Drop a data object onto the canvas
3. Change the data objects name
4. Remove the data object again

Test Coverage

File	% Stmts	% Branch	% Funcs	% Lines
main/packages/bpmn/bpmn-data-object	94.33	100	66.66	94.33
bpmn-data-object-component.tsx	100	100	100	100
bpmn-data-object.ts	84.21	100	50	84.21

Screenshots