Fixes for Gemini inside Vertex (#11511)

llama-index-core/llama_index/core/base/llms/types.py

llama-index-core/llama_index/core/utilities/gemini_utils.py

...s/llama-index-llms-gemini/llama_index/llms/gemini/base.py

.../llama-index-llms-gemini/llama_index/llms/gemini/utils.py

...-integrations/llms/llama-index-llms-gemini/pyproject.toml

...s/llama-index-llms-vertex/llama_index/llms/vertex/base.py

.../llama-index-llms-vertex/llama_index/llms/vertex/utils.py

...-integrations/llms/llama-index-llms-vertex/pyproject.toml