[Integration] NVIDIA AI Playground (#14648)

Description: Added NVIDIA AI Playground Initial support for a selection of models (Llama models, Mistral, etc.)

Dependencies: These models do depend on the AI Playground services in NVIDIA NGC. API keys with a significant amount of trial compute are available (10K queries as of the time of writing).

H/t to @VKudlay

docs/docs/integrations/providers/nv_aiplay.mdx

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+# NVIDIA AI Playground
+
+> [NVIDIA AI Playground](https://www.nvidia.com/en-us/research/ai-playground/) gives users easy access to hosted endpoints for generative AI models like Llama-2, Mistral, etc. This example demonstrates how to use LangChain to interact with supported AI Playground models.
+
+These models are provided via the `langchain-nvidia-aiplay` package.
+
+## Installation
+
+```bash
+pip install -U langchain-nvidia-aiplay
+```
+
+## Setup and Authentication
+
+- Create a free account at [NVIDIA GPU Cloud](https://catalog.ngc.nvidia.com/).
+- Navigate to `Catalog > AI Foundation Models > (Model with API endpoint)`.
+- Select `API` and generate the key `NVIDIA_API_KEY`.
+
+```bash
+export NVIDIA_API_KEY=nvapi-XXXXXXXXXXXXXXXXXXXXXXXXXX
+```
+
+```python
+from langchain_nvidia_aiplay import ChatNVAIPlay
+
+llm = ChatNVAIPlay(model="mixtral_8x7b")
+result = llm.invoke("Write a ballad about LangChain.")
+print(result.content)
+```
+
+## Using NVIDIA AI Playground Models
+
+A selection of NVIDIA AI Playground models are supported directly in LangChain with familiar APIs.
+
+The active models which are supported can be found [in NGC](https://catalog.ngc.nvidia.com/orgs/nvidia/teams/ai-foundation/). In addition, a selection of models can be retrieved from `langchain.<llms/chat_models>.nv_aiplay` which pull in default model options based on their use cases. 
+
+**The following may be useful examples to help you get started:**
+- **[`ChatNVAIPlay` Model](/docs/integrations/chat/nv_aiplay).**
+- **[`NVAIPlayEmbedding` Model for RAG Workflows](/docs/integrations/text_embeddings/nv_aiplay).**

libs/partners/nvidia-aiplay/.gitignore

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+__pycache__

libs/partners/nvidia-aiplay/LICENSE

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+MIT License
+
+Copyright (c) 2023 LangChain, Inc.
+
+Permission is hereby granted, free of charge, to any person obtaining a copy
+of this software and associated documentation files (the "Software"), to deal
+in the Software without restriction, including without limitation the rights
+to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+copies of the Software, and to permit persons to whom the Software is
+furnished to do so, subject to the following conditions:
+
+The above copyright notice and this permission notice shall be included in all
+copies or substantial portions of the Software.
+
+THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+SOFTWARE.

libs/partners/nvidia-aiplay/Makefile

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+.PHONY: all format lint test tests integration_tests help
+
+# Default target executed when no arguments are given to make.
+all: help
+
+# Define a variable for the test file path.
+TEST_FILE ?= tests/unit_tests/
+
+test:
+	poetry run pytest $(TEST_FILE)
+
+tests:
+	poetry run pytest $(TEST_FILE)
+
+check_imports: $(shell find langchain_nvidia_aiplay -name '*.py')
+	poetry run python ./scripts/check_imports.py $^
+
+integration_tests:
+	poetry run pytest tests/integration_tests
+
+
+######################
+# LINTING AND FORMATTING
+######################
+
+# Define a variable for Python and notebook files.
+PYTHON_FILES=.
+MYPY_CACHE=.mypy_cache
+lint format: PYTHON_FILES=.
+lint_diff format_diff: PYTHON_FILES=$(shell git diff --name-only --diff-filter=d master | grep -E '\.py$$|\.ipynb$$')
+lint_package: PYTHON_FILES=langchain_nvidia_aiplay
+lint_tests: PYTHON_FILES=tests
+lint_tests: MYPY_CACHE=.mypy_cache_test
+
+lint lint_diff lint_package lint_tests:
+	./scripts/check_pydantic.sh .
+	./scripts/lint_imports.sh
+	poetry run ruff .
+	[ "$(PYTHON_FILES)" = "" ] || poetry run ruff format $(PYTHON_FILES) --diff
+	[ "$(PYTHON_FILES)" = "" ] || poetry run mypy $(PYTHON_FILES)
+
+format format_diff:
+	poetry run ruff format $(PYTHON_FILES)
+	poetry run ruff --select I --fix $(PYTHON_FILES)
+
+spell_check:
+	poetry run codespell --toml pyproject.toml
+
+spell_fix:
+	poetry run codespell --toml pyproject.toml -w
+
+######################
+# HELP
+######################
+
+help:
+	@echo '----'
+	@echo 'format                       - run code formatters'
+	@echo 'lint                         - run linters'
+	@echo 'test                         - run unit tests'
+	@echo 'tests                        - run unit tests'
+	@echo 'test TEST_FILE=<test_file>   - run all tests in file'