Prevent duplicated help menu entries

[pinussilvestrus]

Originated from #3035.

This prevents duplicated help menu entries in the backend.

Closes #3032

[barmac]

If we merge this PR, no link will be displayed when --disable-platform flag is set. We already don't display tutorial links for BPMN in such a situation, which I think could be considered as a bug as well.

[barmac]

So perhaps we should display/hide links based on the --disable-<file-type> flags, not based on provider appearance.

[pinussilvestrus]

Very good catch 👍 I will propose something.

[pinussilvestrus]

What about ensuring the help menus only got added once in the TabsProvider:

const dmnProvider = (this.providersByFileType['dmn'] || [])[0];
if (dmnProvider) {
  dmnProvider.getHelpMenu = () => DMN_HELP_MENU;
}

const bpmnProvider = (this.providersByFileType['bpmn'] || [])[0];
if (bpmnProvider) {
  bpmnProvider.getHelpMenu = () => BPMN_HELP_Menu;
}

This way, we don't depend on --disable-platform | --disable-zeebe flags. Looks a bit like monkey-patching, but we are anyway manipulating the providers via flags this way.

[barmac]

This should solve the issue. We could also implement it on the backend: https://github.com/camunda/camunda-modeler/blob/develop/app/lib/menu/menu-builder.js#L549

[pinussilvestrus]

As the backend does not know about BPMN, or DMN, we could definitely filter for duplicates, e.g. via label, or label + action.

[pinussilvestrus]

I updated the PR to prevent duplicates in the backend. Added @smbea as any other is on vacation 🙂

[smbea]

I think this looks good 🚀