feat: Implement AWS policy variables support (#1131)

Co-authored-by: houseme <housemecn@gmail.com>
Co-authored-by: loverustfs <hello@rustfs.com>

crates/e2e_test/src/policy/README.md

@@ -0,0 +1,39 @@
+# RustFS Policy Variables Tests
+
+This directory contains comprehensive end-to-end tests for AWS IAM policy variables in RustFS.
+
+## Test Overview
+
+The tests cover the following AWS policy variable scenarios:
+
+1. **Single-value variables** - Basic variable resolution like `${aws:username}`
+2. **Multi-value variables** - Variables that can have multiple values
+3. **Variable concatenation** - Combining variables with static text like `prefix-${aws:username}-suffix`
+4. **Nested variables** - Complex nested variable patterns like `${${aws:username}-test}`
+5. **Deny scenarios** - Testing deny policies with variables
+
+## Prerequisites
+
+- RustFS server binary
+- `awscurl` utility for admin API calls
+- AWS SDK for Rust (included in the project)
+
+## Running Tests
+
+### Run All Policy Tests Using Unified Test Runner
+
+```bash
+# Run all policy tests with comprehensive reporting
+# Note: Requires a RustFS server running on localhost:9000
+cargo test -p e2e_test policy::test_runner::test_policy_full_suite -- --nocapture --ignored  --test-threads=1
+
+# Run only critical policy tests
+cargo test -p e2e_test policy::test_runner::test_policy_critical_suite -- --nocapture --ignored --test-threads=1
+```
+
+### Run All Policy Tests
+
+```bash
+# From the project root directory
+cargo test -p e2e_test policy:: -- --nocapture --ignored --test-threads=1
+```