ParallelAllocWorkers is a configuration option used in both AWS and
Azure allocators, therefore it is declared as a cell.Config in the
operator IP allocator provide cell.

Azure and AWS allocators will be added in a subsequent commit and will
relay on this shared config.

Signed-off-by: Fabio Falzoi <fabio.falzoi@isovalent.com>

Add a cell to implement the AlibabaCloud allocator. Also, make the
AlibabaCloud operator options part of the cell configuration.  The value
of those options are passed down to the AlibabaCloud allocator. The
allocator still uses the global defined option values: this will be
updated in a subsequent commit where the old operator IPAM allocator
code will be removed.

Signed-off-by: Fabio Falzoi <fabio.falzoi@isovalent.com>

Add a cell to implement the AWS allocator. Also, make the AWS operator
options part of the cell configuration.  The value of those options are
passed down to the AWS allocator. The allocator still uses the global
defined option values: this will be updated in a subsequent commit where
the old operator IPAM allocator code will be removed.

AWSMaxResultsPerCall and AWSPaginationEnabled options are kept in the
old file and added through the flags hooks. This is done in order to
keep the backward compatibility with the AWSPaginationEnabled logic,
that requires to check if the option is explicitly set. Since a
reference to the viper instance is needed for that, and the hive does
not expose it, we keep them as is for now.

Signed-off-by: Fabio Falzoi <fabio.falzoi@isovalent.com>

Add a cell to implement the Azure allocator. Also, make the Azure
operator options part of the cell configuration.  The value of those
options are passed down to the Azure allocator. The allocator still uses
the global defined option values: this will be updated in a subsequent
commit where the old operator IPAM allocator code will be removed.

Signed-off-by: Fabio Falzoi <fabio.falzoi@isovalent.com>

Move TestPodCIDRAllocatorOverlap to operator/pkg/ipam alongside the
CiliumNode watcher implementation.

Signed-off-by: Fabio Falzoi <fabio.falzoi@isovalent.com>

Remove the old code to start the needed IPAM allocator in favor of the
new modular implementation. Also, remove all the global options specific
to a particular IPAM mode to rely on the options defined in the cells
and fix the tests accordingly.

Signed-off-by: Fabio Falzoi <fabio.falzoi@isovalent.com>