vty: re-add 'timeout-ping' and 'timeout-pong' as dummy commands

Legacy VTY commands were removed in commit
c74a5616bf1c77ac40ddd92f4927dca7a1b45bc8
== I5cf3fec31cc774c902f3cfe6d16fb85ef301694a

Removing the dead VTY commands currently breaks our ttcn3-bts-test and is
likely to create problems with users of osmo-bsc, when their config osmo-bsc
stops working with a mere upgrade.

Instead, add deprecated dummy commands that don't do anything, to not break
existing configs.

Catch all of these legacy commands:
 timeout-ping <number>
 timeout-pong <number>
 timeout-ping advanced
 no timeout-ping
 no timeout-ping advanced
by defining
 timeout-ping ARG
 timeout-pong ARG
 no timeout-ping [ARG]

I verified manually that starting osmo-bsc with all the abovementioned VTY
commands in the config file works (and produces the deprecation messages).

Change-Id: I95a5bad1ade66ded849cfc20bebb7fc522aecc38
1 file changed