Do not require IntelliJ IDEA to index node_modules

[anssit]

Indexing node_modules is slow, and many developers would prefer to leave it unindexed. However, Vaadin Designer currently depends on indexed node_modules in its web component discover process.

Designer web components discovery should be changed so that it is based on the information in package.json. Designer should check the dependencies specified in package.json for web components instead of scanning the whole node_modules folder.

In addition to relaxing the indexing requirement, this change should result in a considerably faster web components scanning process, both in IntelliJ IDEA and Eclipse. Yet another benefit over directly scanning node_modules is that it will then become easier to further develop the implementation so that the components can be looked up from another source, like CDN.