lvsb_base: Add sandbox options mapper

The patch fixes several small issues firstly, for example, to avoid
the make_sandbox_command_line() is called twice, and should append
option for flag rather than argument. And then the patch implement
a sandbox options mapper, which will help complex options testing.

Signed-off-by: Alex Jia <ajia@redhat.com>
lvsb: support complex options sandboxes

Refactor codes to support complex sandbox testing.

Signed-off-by: Alex Jia <ajia@redhat.com>
virttest: build a object with counts generator

Implement a generator based on object and counts.

Signed-off-by: Alex Jia <ajia@redhat.com>