Rename netconf-impl to netconf-server

netconf-impl contains classes (in the .osgi) package, which really are related to netconf-server. These get activated in mdsal-netconf-impl via blueprint. Separate these classes out into an OSGi DS-driven netconf-server package. Eliminate blueprint from mdsal-netconf-impl, leaving it empty, but retain dependency compatibility by depending on netconf-server.

Note netconf-server should live in /protocol directory.

Based on below, this issue deals with just rename and movement of code. The blueprint stuff will be dealt with separately.