fix: introduce url & header checking from the config.

[drcgjung]

WHAT

Improves url and header checking in AgentConfig.

WHY

CodeQL may complain about some potential SSF traps.

FURTHER NOTES

Wrt to sanitizing other dynamic SSF sources which CodeQL may not correctly detect, please have a look at:

• https://github.com/eclipse-tractusx/knowledge-agents-edc/blob/1d51fed97cd2aa379d452f54b5a9175eb65ab72e/agent-plane/agent-plane-protocol/src/main/java/org/eclipse/tractusx/agents/edc/http/DelegationServiceImpl.java#L214 ff
• https://github.com/eclipse-tractusx/knowledge-agents-edc/blob/1d51fed97cd2aa379d452f54b5a9175eb65ab72e/agent-plane/agent-plane-protocol/src/main/java/org/eclipse/tractusx/agents/edc/http/DelegationServiceImpl.java#L218 ff