This PR adds support for the -u/--uri flag to memtier_benchmark, enabling URI-based connection strings similar to redis-benchmark and redis-cli.

Changes

• URI parsing: Support for redis://[username[:password]@]host[:port][/db-number] and rediss:// (TLS) formats
• Command line integration: Added -u/--uri option with proper help text and man page documentation
• Configuration: URI components automatically populate existing config fields (server, port, authenticate, select_db, tls)
• Conflict detection: Warnings when both URI and individual connection flags are specified, with URI taking precedence
• Error handling: Proper validation and error messages for malformed or invalid URIs

Testing

Added python tests covering both positive cases (valid URI connections) and negative cases (invalid URIs that properly exit with error codes).

Usage

# Basic connection
memtier_benchmark -u redis://localhost:6379

# With authentication and database selection  
memtier_benchmark -u redis://user:pass@localhost:6380/2

# TLS connection
memtier_benchmark -u rediss://localhost:6380

Testing

## positive tests

TEST=tests_oss_simple_flow:test_uri_connection ./tests/run_tests.sh

## negative tests
TEST=tests_oss_simple_flow:test_uri_connection_negative ./tests/run_tests.sh