feat: allow public access to claims bucket (#82)

Per the description here:
https://docs.aws.amazon.com/AmazonS3/latest/userguide/access-control-block-public-access.html#access-control-block-public-access-options
- this PR enables public read access to the bucket. It allows the
indexing service to read claims by URL without any special handling for
these legacy claims.

stacks/bucket.js

@@ -4,6 +4,20 @@ import { Bucket as S3Bucket } from 'sst/constructs'
  * @param {import('sst/constructs').StackContext} config
  */
 export function Bucket ({ stack }) {
-  const claimsBucket = new S3Bucket(stack, 'claims-v1')
+  const claimsBucket = new S3Bucket(stack, 'claims-v1', {
+    cors: true,
+    cdk: {
+      bucket: {
+        blockPublicAccess: {
+          // do not allow public write access
+          blockPublicAcls: true,
+          ignorePublicAcls: true,
+          // allow public read access
+          blockPublicPolicy: false,
+          restrictPublicBuckets: false
+        }
+      }
+    }
+  })
   return { claimsBucket }
 }