Add retries w/ exponential backoff for databricks provider

[bkvarda]

Adds retries w/ exponential backoff and configurable settings for Databricks provider for common transient errors

Example

 2025-06-03T04:07:40.714284Z  WARN goose::providers::databricks: Rate limit exceeded (attempt 1/6): Some(Object {"error_code": String("REQUEST_LIMIT_EXCEEDED"), "message": String("REQUEST_LIMIT_EXCEEDED: Exceeded workspace rate limit for databricks-claude-3-7-sonnet. Please use a provisioned throughput Foundation Model APIs endpoint for a higher rate limit.")}). Retrying after backoff...
    at crates/goose/src/providers/databricks.rs:370

  2025-06-03T04:07:41.585127Z  WARN goose::providers::databricks: Rate limit exceeded (attempt 2/6): Some(Object {"error_code": String("REQUEST_LIMIT_EXCEEDED"), "message": String("REQUEST_LIMIT_EXCEEDED: Exceeded workspace rate limit for databricks-claude-3-7-sonnet. Please use a provisioned throughput Foundation Model APIs endpoint for a higher rate limit.")}). Retrying after backoff...

[michaelneale]

thanks @bkvarda - need some rust format/clippy checks to run - but this looks ok to me - I can fix it up if it is ok to push to your branch to update things? I think can consoldate it with #2763 change perhaps (which just ads some more messages).
But appreciate this, I hit this a lot!

[bkvarda]

@michaelneale hopefully i fixed the clippy/cargo fmt issues.

[michaelneale]

seems ok to me from what I can tell