fix: Fix BedrockChatGenerator to be able to handle multiple tool calls from one response (#1711)

* Adding more tests

* Finish fix for repairing tool result messages

* Some refactoring

* Update test

* Fix linting and mypy

* Update more integration tests

* Test streaming for just cohere

* Refactoring the streaming processing

* Start adding conversion of event to streaming chunk

* Some refactoring

* More refactoring

* Finish conversion of event into streaming chunk

* Update test

* Fix test

* Fix linting

* Refactoring and removing code

* Fix formatting

* Improve docstrings

* test update

* Adding some comments

Author: sjrl