arch: Add Dual-redundant Core Lock-step (DCLS) configuration.

[stephanosio]

Add a new Kconfig configuration for specifying Dual-redundant Core
Lock-step (DCLS) processor topology.

Signed-off-by: Stephanos Ioannidis root@stephanos.io

NOTE:

• Separated out from Cortex-R Port Improvement for 2.2 #19698 for timely review and merging.
• For more details on why this config should go into arch/Kconfig rather than arch/arm/Kconfig or arch/arm/cortex_r/Kconfig, refer to Cortex-R Port Improvement for 2.2 #19698 (comment).

[nashif]

we prefer to get the Kconfig with the implementation, otherwise @ulfalizer has scripts that wipe those automatically if they are not being used.

[stephanosio]

otherwise @ulfalizer has scripts that wipe those automatically if they are not being used.
well, that sounds scary.

@nashif I will close this PR and integrate this commit into #20473, which is a direct user of this Kconfig symbol.