psa: Add a script to validate PSA targets
psa: Add a script to validate PSA targets

Add a script to parse `targets.json` to identify PSA targets and ensure
mandatory parameters are configured correctly for all PSA targets.

Signed-off-by: Devaraj Ranganna <53e2fcb007e5c6e2caf46b91114119a655266f64@arm.com>

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