chore(event-handler): align implementation with other runtimes

[dreamorosi]

Summary

Changes

Please provide a summary of what's being changed

This PR makes a few targeted changes to the implementation of the BedrockAgentFunctionResolver upcoming feature, specifically:

• removed 5 tools limit on the grounds that customers can create multiple action groups in their agents backed by the same Lambda function, and thus there's no point in restricting the numbers of tools - we'll however call out the 5 tools limit in the docs (separate PR)
• made sure session, prompt, and knowledge base configurations are always propagated in responses
• removed decorator implementation because of the unsolved bug described in Bug: AppSyncEventsResolver decorators break scope #3973
• added a new BedrockFunctionResponse class that is both used under the hood by the resolver class to build responses and can be used by customers to fully customize the response with things like session attributes of statuses
• added docstring comments to all types, classes, and methods & added the submodule to API docs reference

Please add the issue number below, if no issue is present the PR might get blocked and not be reviewed

Issue number: closes #3988

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[leandrodamascena]

LGTM

[sonarqubecloud]

Quality Gate passed

Issues
0 New issues
0 Accepted issues

Measures
0 Security Hotspots
0.0% Coverage on New Code
0.0% Duplication on New Code

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