Integrate with DotNetNuke.R7

[roman-yagodin]

Some template parts from lib and components folders must be replaced by DotNetNuke.R7 shared library, when it gets somewhat stable. This should make templates lighter and greatly reduce amount of duplicated code between various R7 extensions.

[roman-yagodin]

DotNetNuke.R7 should be referenced via NuGet package (which already created), waiting DNN 7.4.2 to upgrade main production site to it from 7.1.2 (for which there was no corresponding DNN NuGet package).