Refactor architecture to support development scenario

[blcham]

Currently, s-pipes-editor-ui has its own forwarding to to backend service with variable SERVICE_URL dynamically configured in nginx.conf. This is not possible to use in development scenario where we need to point to a service that is external to the s-pipes-editor-ui container.

A/C:

• we would like to have a docker-compose file where we could switch some of the components for external ones (e.g. s-pipes-editor-rest service for http://localhost:18115)
• we would like to be able to debug individual container services as well

[blcham]

@blcham @kostobog @rodionnv

[blcham]

The proposal:

• instead of internal spe-nginx we create nginx shared for all services and we connect this service to host network in development scenario.

Design considerations:

• it does not make sense to have localhost:3000/rest hardcoded because even in development environment you cannot deploy backend to same port as UI => backend URL should not be hardcoded

[blcham]

So the solution would have to change spe-ui in the following way:

• make backend URL parametrizable and defined in /config.js
• in docker distribution config.js is provided in runtime -- it is created in docker entrypoint from config.js.template substituting ENV variables
• in npm, build config.js is substituted in build time (e.g. using webpack plugins)