code cleanup (1/10): remove &FAI:: from &FAI::push_command() [+rationale]

This patchset removes &FAI:: from all locally defined functions. Since
these functions are defined in the same file there is no need to refer
to the file's namespace.

The prevalent convention to call a functions is:

  'local' function
    -> use just the function name                function()

  'foreign' function
    -> import function into local namespace      function()
    -> explicitely refer to namespace            Namespace::function()

While it makes no difference to the Perl interpreter to use a different
convention it just confuses the potential reader - at the very least it
creates a need to manually track functions that are defined locally and
functions that are defined somewhere else.

Another reason for this patch is to gradually convert the current code
into a state where there is no need for everything to live in the same
namespace anymore. At the very least it makes it obvious where foreign
functions are coming from - instead of having to grep Init.pm, Exec.pm
or any other module for a specific function.

Command used for this patch:
  sed -i 's/&FAI::push_command/push_command/' lib/setup-storage/Commands.pm
code cleanup (2/10): remove &FAI:: from &FAI::build_mkfs_commands()

Command used for this patch:
  sed -i 's/&FAI::build_mkfs_commands/build_mkfs_commands/' lib/setup-storage/Commands.pm
code cleanup (3/10): remove &FAI:: from &FAI::handle_oldstyle_encrypt_device

Command used for this patch:
  sed -i 's/&FAI::handle_oldstyle_encrypt_device/handle_oldstyle_encrypt_device/' lib/setup-storage/Commands.pm
code cleanup (4/10): remove &FAI:: from &FAI::set_partition_flag_on_phys_dev

Command used for this patch:
  sed -i 's/&FAI::set_partition_flag_on_phys_dev/set_partition_flag_on_phys_dev/' lib/setup-storage/Commands.pm
code cleanup (5/10): remove &FAI:: from &FAI::cleanup_vg

Command used for this patch:
  sed -i 's/&FAI::cleanup_vg/cleanup_vg/' lib/setup-storage/Commands.pm
code cleanup (6/10): remove &FAI:: from &FAI::create_volume_group

Command used for this patch:
  sed -i 's/&FAI::create_volume_group/create_volume_group/' lib/setup-storage/Commands.pm
code cleanup (7/10): remove &FAI:: from &FAI::setup_logical_volumes

Command used for this patch:
  sed -i 's/&FAI::setup_logical_volumes/setup_logical_volumes/' lib/setup-storage/Commands.pm
code cleanup (8/10): remove &FAI:: from &FAI::get_preserved_partitions

Command used for this patch:
  sed -i 's/&FAI::get_preserved_partitions/get_preserved_partitions/' lib/setup-storage/Commands.pm
code cleanup (9/10): remove &FAI:: from &FAI::rebuild_preserved_partitions

Command used for this patch:
  sed -i 's/&FAI::rebuild_preserved_partitions/rebuild_preserved_partitions/' lib/setup-storage/Commands.pm
code cleanup (10/10): remove &FAI:: from &FAI::setup_partitions

Command used for this patch:
  sed -i 's/&FAI::setup_partitions/setup_partitions/' lib/setup-storage/Commands.pm
replace recurrent calls to &FAI::make_device_name() with a variable
remove linebreak (prepare for further modification)
replace $FAI::current_config{$disk}...{begin_byte} with variable
replace $FAI::current_config{$disk}...{end_byte} with variable
convert (\%FAI::configs)->{$config} into $FAI::configs{$config}

That's a strange way to access the hash '%FAI::configs'.
convert \%{ $FAI::configs{$config}{volumes}{<key>} } into $FAI::configs{$config}{volumes}{<key>}

That's a strange way to access the hash reference stored in
'$FAI::configs{$config}{volumes}{<key>}'.
move 'use POSIX' to file header

The use-statement will always processed, regardless of it's position.
It's preferable to move all use-statements to the file header in order
to be able to see all requirements at a glance.

Example:

  if (<condition>) {
    use <lib>;
    ...
  }

and

  sub function {
    use <lib>;
    ...
  }

are equal to

  use <lib>;
  if (<condition>) {
    ...
  }

and

  use <lib>;
  sub function {
    ...
  }
provide unit tests for build_disk_commands() and build_lvm_commands() (Commands.pm)

(It was necessary to modify Commands.pm to provide a stable output.)
provide unit tests for build_raid_commands() and build_cryptsetup_commands() (Commands.pm)

(Test coverage is now 67%. Let the fun begin.)
remove unused function set_partition_table_deps()