ssb: Add some plausible API and a table for storing instance-wide blocks.

core/core.js

@@ -494,18 +494,34 @@ async function getProcessBlob(blobId, key, options) {
 					);
 				}
 			};
-			imports.ssb.swapWithServerIdentity = function (id) {
-				if (
-					process.credentials &&
-					process.credentials.session &&
-					process.credentials.session.name
-				) {
-					return ssb.swapWithServerIdentity(
-						process.credentials.session.name,
-						id
+			if (process.credentials?.permissions?.administration) {
+				imports.ssb.swapWithServerIdentity = function (id) {
+					if (
+						process.credentials &&
+						process.credentials.session &&
+						process.credentials.session.name
+					) {
+						return ssb.swapWithServerIdentity(
+							process.credentials.session.name,
+							id
+						);
+					}
+				};
+				imports.ssb.addBlock = async function (id) {
+					await imports.core.permissionTest(
+						'modify_blocks',
+						`Block ${id}.`
 					);
+					await ssb_internal.addBlock(id);
 				}
-			};
+				imports.ssb.removeBlock = async function (id) {
+					await imports.core.permissionTest(
+						'modify_blocks',
+						`Unblock ${id}.`
+					);
+					await ssb_internal.removeBlock(id);
+				}
+			}
 
 			if (
 				process.credentials &&