Improving documentation for local dev setup

[neildsouth]

Sensitive Credential Checks

• As the author of these changes, I have checked for any sensitive credentials prior to this review being requested.
• As a reviewer of these changes, I have checked for any sensitive credentials prior to approving this merge.

Motivation and Context

Improving the documentation to allow an easier setup for new devs to the project.

Description

aligned the keycloak client name used for local deployment, now its consistently "management-node".
Fix up curl commands to now pass necessary certs.
Added missing Keycloak Realm file for import
Improved documentation around creation of this realm, if not importing it.

How Has This Been Tested?

Ran though the Readme again and followed the implementation to ensure correct outcome, this was done on a Windows 11 machine under WSL2.

Checklist:

• It contains only changes required by issue (does not contain other PR)
• Includes link to an issue (if apply)
• I have added tests to cover my changes.

[sonarqubecloud]

Quality Gate failed

Failed conditions
E Security Rating on New Code (required ≥ A)

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