Add stream support for Bedrock Anthropic

[KoStard]

Description

• Adding dependency on official aws-sdk bedrock runtime library to have better support for the API
• Using stream API for Bedrock Anthropic

Checklist

• [x] The base branch of this PR is preview, rather than main

[KoStard]

https://github.com/continuedev/continue/issues/1211

[sestinj]

Nice work @KoStard ! Just getting around to reviewing this. Will finish testing later today and then merge