split up configparser prepare_* into separate func

configparser prepare_zerovm_files() was too specific for standalone case
made it more generic and added 3 specific funcs:

- prepare_for_standalone()
- prepare_for_daemon()
- prepare_for_forked()

now different set of manifest, nvram and other support files is generated
depending on what type of zerovm execution is required

it also fixes inconsistency in handling manifest for the case where daemon was dead for some reason and restarted from middleware after unsuccessful socket connect