Add local environment in angular environments for local art build

[drewnielson]

• Adding local environment in angular environments: src/environments/environment.local.ts
• Adding local configuration in angular.json>projects>ART>architect>build>configurations
• Adding build:art:local script in package.json to facilitate local ART build

To build ART locally run the following, in order:
npm run build:art:local
bundle exec jekyll serve [or npm run start]