Add `aws_http_client` and `bedrock` crates (#25490)

This PR adds new `aws_http_client` and `bedrock` crates for supporting
AWS Bedrock.

Pulling out of https://github.com/zed-industries/zed/pull/21092 to make
it easier to land.

Release Notes:

- N/A

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Co-authored-by: Shardul Vaidya <cam.v737@gmail.com>
Co-authored-by: Anthony Eid <hello@anthonyeid.me>