[META] Extension Security Management

[peternied]

Extensions are a new concept in OpenSearch and the security plugin needs ways to reference or make decisions about them. Capturing all of those topics in this meta issue.

Application Scopes

• [Question] How do administrators control what extensions can do? #2587
• [Question] How can requests coming from an extension interact with the OpenSearch cluster?  #2572
  • Only via OnBehalfOf tokens or ServiceAccount
• [Question] What application scopes will there be for extensions? #2644

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Service Accounts

• Add Extension Service Accounts #2584
• [Question] How should extension permissions be defined and where? #2502
• [Question] How should service account permissions be stored and where? #2566
• [Question] Granting Permissions to Extensions #2552
• [Question] Service Account Specifications #2597