[BUG] The browser field in package.json is incorrect

[tbouffard]

Describe the bug
The current value of the browser field in the package.json is set to the IIFE bundle file and it is a wrong value. The IIFE bundle cannot be used by bundlers and if so, there are errors at runtime.

The current value makes the bpmn-visualization integration painful for bundlers that use the browser field in priority in web projects. For instance, this is the behavior of Webpack and Parcel.
Their default configuration does not work out of the box, so users may give up prior creating an issue/question and/or check the bpmn-visualization-examples repository.

We have found and documented workarounds, but they have significant drawbacks.

• Parcel
  • it is possible to configure an alias in the package.json file to use the ESM bundle. See [FEAT] Add a project to demonstrate integration with Parcel bpmn-visualization-examples#338 (comment).
  • This workaround only applies to bpmn-visualization and has no impact on the rest of the project. However, it causes [INFRA] The Parcel TS project is not udpated correctly by the script updating the bpmn-visualization version bpmn-visualization-examples#351
• Webpack
  • users have to configure mainFields in the resolve configuration as shown in https://github.com/process-analytics/bpmn-visualization-examples/blob/v0.26.1/projects/javascript-vanilla-with-webpack/webpack.config.js#L29-L32
  • It impacts all dependencies of a project: using the browser field may be mandatory for other dependencies and this may prevent integration of bpmn-visualization in such projects. See this feedback about an Angular project: TypeError when calling the BpmnVisualization constructor in a Angular 11 project #2221
  • The only alternative is to edit the package.json in the local node_modules (manually, with scripts, with https://www.npmjs.com/package/patch-package, ....) to use the ESM bundle instead. This makes the integration hard to do.

Proposal
Set the field to ESM or remove it as we already configure the module field
Here is the purpose of the browser field according to the npm documentation

If your module is meant to be used client-side the browser field should be used instead of the main field. This is helpful to hint users that it might rely on primitives that aren't available in Node.js modules. (e.g. window)

Additional context
See also #2230