P3: Bucket Policy implementation complete

- BucketPolicy struct with Version + Statement array
- PolicyStatement: Effect, Principal, Action, Resource, Condition
- Principal matching (wildcard + user-specific)
- Action/Resource pattern matching with wildcards
- GetBucketPolicy: GET /s3/policy/:bucket
- PutBucketPolicy: PUT /s3/policy/:bucket
- DeleteBucketPolicy: DELETE /s3/policy/:bucket
- Policy persistence to data/s3_policies/:bucket/policy.json
- check_bucket_policy() for authorization
- 6 unit tests

Tests: 299 passed, 0 failed

markbase-core/src/lib.rs

@@ -16,6 +16,7 @@ pub mod rsync;
 pub mod s3;
 pub mod s3_auth;
 pub mod s3_config;
+pub mod s3_policy;
 pub mod s3_xml;
 pub mod scan;
 pub mod server;