Bpmn.io plugin for showing variable operations

[TamaraGunkel]

From issue #139 (@cl-a-us )

I like the idea of a bpmn.io plugin, if the implementation is not to complex.
Nevertheless, we can start with own attributes in the bpmn xml file and add a representation (i.e. a bpmn.io plugin) in future.
As a result of a vpav run a new bpmn file can be exported and can be used to replace the bpmn file in the process application.

A plugin, that we might provide in future, can replace the view ´process variables´ in the vpav validationResult.html.

In that case, I propose a plugin, which displays read, write, and delete access of process variables similar to the turquoise bubbles/badges (class=¨badge-variable-operations ¨) we display right now. A click on a badge would open the properties panel and show which variables are accessed, the type of access (read, write or delete), and the time of access (start listener, end listener, (delegate) implementation …). We could also distinguish between manual and automatic recognition of variables. Manual defined entries could be added, edited, and removed, whereas variables discovered by vpav could only be disabled.
The advantage of the plugin would be, that it could be installed e.g. in camunda standalone modeler, in online modeler, (like the confluence modeler), or even in camunda cockpit.

Having a plugin in mind, own attributes in the bpmn xml file should define the following information (please extend the list, if I miss something):

Variable name
Time/point of access (start listener, end listener, (delegate) implementation …)
Discovery(?) type: vpav (automatic) vs. manual
Disabled: true/false (to mark false positives)
Timestamp
Entry ID: (to match false positives)
A new vpav run should replace all ´old´ automatic discovered entries (except for disabled entries).