[DPP] Rename "DPP" public API to "Easy Connect"

Rename all DPP public API and constants to use Easy Connect naming,
which is the WFA public technology name.

Bug: 122851551
Test: atest DppManagerTest
Test: act.py -c ../WifiDppConfig.json -tc WifiDppTest
Change-Id: I706b4220edebf578c0d7eedf0b4c21d032c22e56
3 files changed