feat(sdk): Handle subdirectories for the folder in S3Validator (#4101)

### Description

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What's included in this PR?
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- Set the folder in the `S3Config` to include any subdirectories and not
just the first folder
- This brings the SDK inline with current behavior in the agents

### Drive-by changes

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Are there any minor or drive-by changes also included?
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### Related issues

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- Fixes #[issue number here]
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- Fixes #4100 

### Backward compatibility

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Are these changes backward compatible? Are there any infrastructure
implications, e.g. changes that would prohibit deploying older commits
using this infra tooling?

Yes/No
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Yes

### Testing

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What kind of testing have these changes undergone?

None/Manual/Unit Tests
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Manual

.changeset/tiny-lions-kiss.md

@@ -0,0 +1,5 @@
+---
+'@hyperlane-xyz/sdk': patch
+---
+
+Handle subdirectories for the folder in S3Validator class

typescript/sdk/src/aws/validator.ts

@@ -39,7 +39,7 @@ export class S3Validator extends BaseValidator {
         const s3Config = {
           bucket: pieces[0],
           region: pieces[1],
-          folder: pieces[2],
+          folder: pieces.slice(2).join('/'),
           caching: true,
         };
         const s3Bucket = new S3Wrapper(s3Config);