Making Generation in the Preview pane faster by breaking the one large http get response

- Indexing the generation result for the preview pane in static_generator.js such that multiple http get requests can be fired when user scrolls through the generation code and more content can be generated into the preview pane by chunking a big response into smaller ones.
- Adding routing parameters into the urls to accomodate the above in generation.js
- Updating the generation view from q-input to q scroll area in ZclLayout.vue such that large content can be generated using multiple http get request/reponse when the user scrolls through generation result in the preview pane. Before these updates, large responses can sometimes take several seconds to show up on the UI(preview pane)
- Modifying testing as per the above changes
- JIRA: ZAPP-166