feat: added support for A21 and Amazon Titan models via bedrock api

[awsyshah]

Closes #1076

📑 Description

Included support for A21 & Amazon Titan Model through the bedrock api, using a case structure to enable future flexibility to continue adding other models available. As Bedrock supports quite a few models not adding them all in a single merge.

✅ Checks

• My pull request adheres to the code style of this project
• My code requires changes to the documentation
• I have updated the documentation as required
• All the tests have passed

ℹ Additional Information

[awsyshah]

@AlexsJones did you get a chance to review this for the changes and if it is ok to merge now ?

[AlexsJones]

I need to test it first, will try to get around to it ASAP

[awsyshah]

I need to test it first, will try to get around to it ASAP

@AlexsJones just adding some screenshots of the runs if that helps.

[lenaxia]

If you're looking for a workaround, would suggest using LiteLLM to proxy Bedrock

[JuHyung-Son]

good start! i left some comments

[AlexsJones]

Can you respond to comments and we will merge this next week @awsyshah ?

[awsyshah]

made the key suggest improvement of moving some of the constants to config. The other vars are as per the API or not need outside of the case and hence declared within it. Please review.

[JuHyung-Son]

comments are not fixed

[awsyshah]

comments are not fixed

Hi @JuHyung-Son ,

Sorry for the trouble there, can I request which are the specific ones you want changed.

The first action of moving the constants like maxTokens to config is done right ? or is my understanding / implementation incorrect ?

For Comment 2 , the stop_reason , that call used is as per the documentation from :https://docs.aws.amazon.com/bedrock/latest/userguide/model-parameters-anthropic-claude-messages.html

For Comment 3: The type you have commented on is only used once and that is if it is a a21 model so its defined within the area so as its only ever used there. The rest of the code has not use of it , is it still better to just define it up top even is only ever to be used if the model is one of the A21 one and may not be used otherwise ?

Let me know and I will make the changes so we can have this merged.

Thanks

[JuHyung-Son]

i got it.
LGTM!