Various Improvements

• Refactoring meta request types to have a cleaner implementation/improve cancel functionality stability.
• Added a mitigation for issue where global request limit was being hit, which was negatively impacting performance.

Test updates and tls failure crash fix

• Fix a client creation crash when tls initialization fails
• Mark a few more tls-using tests as net

Import symbol fix

• Correctly imports a missing symbol used in tests

Internal import preparation

• marks a number of tests as network required

Initial Preview Release

Initial preview release of aws-c-s3, a C-based library for communicating with the S3 service, designed for maximizing throughput on high bandwidth EC2 instances.