Implement cta-admin disksystem add/ls/rm commands.

cta-admin logicallibrary ls
cta-admin mountpolicy ls
cta-admin showqueues
cta-admin storageclass ls

Simple repack on CI

Usage: cta-admin --json <command> <subcommand> <options>

For stream commands only (where each line of the result is sent back in
a protocol buffer), return the results in JSON format instead of a
text table.

Better to have all formatting on the client side, so we format the
header and the reponse values in the same place. (Also no need to
send this data over the wire as it's always the same).

OptionStrList takes a filename as its value. It reads the file into a
list of strings in the protobuf. On the server side, the values are
unpacked and made available as std::vector<std::string>.

For example implementation, see "cta-admin repack add"

Default now set to 10s. Note that XRD_TIMEOUTRESOLUTION must be set
<= 10s, otherwise timeout defaults to 15s.