CSPM/KSPM namespace support

[benironside]

Fixes #2207 by updating the CSPM and KSPM documentation to describe the new config setting which enables you to specify a data stream namespace where you want to save an individual integration's data. Also updates the Cloud Posture Dashboard page to reflect the new option to filter by namespace.

[github-actions]

🔍 Preview links for changed docs

• solutions/security/cloud/get-started-with-cspm-for-aws.md
• solutions/security/cloud/get-started-with-cspm-for-azure.md
• solutions/security/cloud/get-started-with-cspm-for-gcp.md
• solutions/security/cloud/get-started-with-kspm.md

[smriti0321]

LGTM

[florent-leborgne]

I think the formatting of the "namespaces" paragraph isn't what you intended. And since it's repeated in many places, it makes sense to use a snippet instead.