Add an opcode name conversion function
Add an opcode name conversion function

Add a function to convert an opcode class name to a source string for the
reason trail, factoring out the code in common with the existing _NameToId
function.

Signed-off-by: Michele Tartara <05f7077a2c6cbbdc4af4ba42e3ef89a0df846179@google.com>
Reviewed-by: Helga Velroyen <2d0126b1ec6f9ec5cbec4a7012aa14faeaef10f5@google.com>

yiannist/ganeti,grnet/snf-ganeti,yiannist/ganeti,ganeti/ganeti,andir/ganeti,leshchevds/ganeti,apyrgio/ganeti,dimara/ganeti,mbakke/ganeti,ganeti/ganeti,bitemyapp/ganeti,bitemyapp/ganeti,leshchevds/ganeti,mbakke/ganeti,leshchevds/ganeti,apyrgio/ganeti,ganeti-github-testing/ganeti-test-1,apyrgio/snf-ganeti,apyrgio/snf-ganeti,yiannist/ganeti,andir/ganeti,ganeti-github-testing/ganeti-test-1,andir/ganeti,ganeti/ganeti,grnet/snf-ganeti,dimara/ganeti,mbakke/ganeti,onponomarev/ganeti,onponomarev/ganeti