feat(firebaseai): auto function calling (#17950)

* add tool_test, add AutoFunctionDeclaration

* first pass of the auto function call

* Added auto function call to sendMessageStream

* update the example test

* fix the auto function calling logic

* Add test for normal stream function calling and auto stream function calling

* Added parallel auto function calling test case

* fix analyzer

* Apply suggestions from code review

Co-authored-by: gemini-code-assist[bot] <176961590+gemini-code-assist[bot]@users.noreply.github.com>

* convert on of the code review suggestion

* clean up and refactor the page

* address review comment

* fix formatter

* fix analyzer

* more fix

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Co-authored-by: gemini-code-assist[bot] <176961590+gemini-code-assist[bot]@users.noreply.github.com>

Author: cynthiajoan