Add functional API test JSON files for the following objects
    - FAST
    - ATM
    - PTM
Also update DSL by adding configure mthodAdd functional API test JSON files for the following objects

Add JSON schemas to the output of the following ubus calls
    - fast.line status and stats
    - atm.link status and stats
    - ptm.line status

Add and update documents for newly added functions
    - DSL configure
    - ATM
    - PTM
    - FAST

Add unit-test cases for the configuration if DSL and ATM

Both positive and negative cases are included

Add UBUS objects for the configuration of DSL and ATM

Add UBUS objects for the status and statistics of ATM and PTM links

Add UBUS objects fast.line.x