Move nsd APIs to their own directory

Nsd APIs are moving to the framework-connectivity JAR, out of the
main framework API definitions. This is seen as an API
incompatibility as the APIs are removed from non-updatable APIs,
and added to updatable APIs.

Bug: 206893064
Test: "for d in public system module-lib; do comm -23 \
       <(sort $d/api/framework-connectivity-tiramisu.txt) \
       <(sort $d/api/android.txt); done" is empty
Merged-In: I2f0aa4fbadb2a7777206902452bfe8a485acdd29
Change-Id: I2f0aa4fbadb2a7777206902452bfe8a485acdd29
8 files changed