Add 'show (bts|trx|ts|lchan)' commands
Add 'show (bts|trx|ts|lchan)' commands

This is more or less a 1:1 import from the BSC side commands.  Having
the commands on the BTS side will allow us to expose information that's
not visible to the BSC [in upcoming, separate patches].

Change-Id: I2a596938849a9c84fe6fedcac5d7f71ee97af575

osmocom/osmo-bts,osmocom/osmo-bts,osmocom/osmo-bts