MCP: [FEAT] virt preconditions handle testprogram_list
MCP: [FEAT] virt preconditions handle testprogram_list

Virt preconditions can now handle testprogram_lists in virt
preconditions. This was requested in BZ #835. I reused parse_testprogram
for both host and guest. This makes the whole parser simpler and
(hopefully) easier to understand.

csdb/Tapper-MCP,tapper/Tapper-MCP,tapper/Tapper-MCP,csdb/Tapper-MCP