Add dashboard

[g4s8]

Move dashboard from https://github.com/artipie/management-api/ repo:

• Java classes https://github.com/artipie/management-api/tree/master/src/main/resources/dashboard
• Templates: https://github.com/artipie/management-api/tree/master/src/main/resources/dashboard

To com.artipie.front.dashboard package. Integrate template renderer https://sparkjava.com/documentation.html#views-and-templates