DCR put allowing to modify unmodifiable SSA metadata

[aka4rKO]

Description:
Currently the DCR put request allows to modify unmodifiable SSA metadata as mentioned in the CDS specification[1]

This issue is created to track the fix for this issue as it was concluded to make this a configuration to enable/disable and to configure custom fields coming in SSA as unmodifiable.

[1] https://consumerdatastandardsaustralia.github.io/standards/#client-registration