missing hamburger dependency

[tobi-or-not-tobi]

With the change of #679 the style lib generates the hamburger menu on the fly. This requires an external dependency to be installed. This is not added to the docs.

We could do different things here:

• add the hamburger npm module as a (peer)dependencies
• refactor the style lib, so that we have a default hamburger type being pre-compiled and only optionally use hamburger library to add more types. We would then add hamburger in the optionalDepenendencies.

We should add a note temporarily to the installation guide, so that hamburger is added as a dependency in any case.

[marlass]

Yesterday after information about the issue I added hamburger as dependency to @spartacus/styles. Release still needs to be merged to master and develop: https://github.com/SAP/cloud-commerce-spartacus-storefront/pull/874

[Xymmer]

closing as fixed in another pr