[Web Components Template] Enable base stylesheet and page specific assets directory that houses SCSS partial and images

[proeung]

The problem

• While developing the landing page for Watson Orchestrate, we realized that there are additional styles that are needed in order for us to assemble a landing page that matches the design.
• Here's an example of the added styles that we've implemented for the Watson Orchestrate Landing page (https://github.ibm.com/Putra-Bonaccorsi/web-components-for-ei/blob/master/src/assets/scss/app.scss).
• This feature allows adopters to easily build and contribute out boilerplate templates that can be used within the ibm.com EI content ecosystem and makes this project the go-to place to adopt landing page designs (eg. Explainer, Solution, etc) for different products.

The solution

• Enable a /assets directory within each template page (eg. /src/pages/page2/assets)
• Adjust the current Webpack configs to watch, live-reload, and build the assets.

Additional information

• Watson Orchestrate/Explainer Template Preview - https://pages.github.ibm.com/Putra-Bonaccorsi/web-components-for-ei/watson-orchestrate.html

cc: @jwitkowski79

[RobertaJHahn]

@proeung Is this a temporary solution until AEM is in place?

[proeung]

@RobertaJHahn Not particularly. This is just an improvement ticket that allows adopters like myself (HC) to utilize this template application and be able to define specific add-on styling that's needed on a particular page template. This work is something that my team can help contribute back, but certainly not a high priority.