chore(docs): Consolidate hooks for copy markdown and notebooks (#5459)

Consolidating the hooks to avoid duplication of logic

We need this change for consolidating js and python content: we need include-markdown to run as a mkdocs plugin before our pipeline (rather than as markdown extension which runs after our hooks plugin).

docs/docs/tutorials/get-started/1-build-basic-chatbot.md

@@ -63,7 +63,7 @@ Next, add a "`chatbot`" node. **Nodes** represent units of work and are typicall
 
 Let's first select a chat model:
 
-{!snippets/chat_model_tabs.md!}
+{% include-markdown "../../../snippets/chat_model_tabs.md" %}
 
 <!---
 ```python

docs/docs/tutorials/get-started/2-add-tools.md

@@ -73,7 +73,7 @@ For the `StateGraph` you created in the [first tutorial](./1-build-basic-chatbot
 
 Let's first select our LLM:
 
-{!snippets/chat_model_tabs.md!}
+{% include-markdown "../../../snippets/chat_model_tabs.md" %}
 
 <!---
 ```python
@@ -286,7 +286,7 @@ For ease of use, adjust your code to replace the following with LangGraph prebui
 - `BasicToolNode` is replaced with the prebuilt [ToolNode](https://langchain-ai.github.io/langgraph/reference/prebuilt/#toolnode)
 - `route_tools` is replaced with the prebuilt [tools_condition](https://langchain-ai.github.io/langgraph/reference/prebuilt/#tools_condition)
 
-{!snippets/chat_model_tabs.md!}
+{% include-markdown "../../../snippets/chat_model_tabs.md" %}
 
 
 ```python hl_lines="25 30"

docs/docs/tutorials/get-started/3-add-memory.md

@@ -154,7 +154,7 @@ The snapshot above contains the current state values, corresponding config, and
   
 Check out the code snippet below to review the graph from this tutorial:
 
-{!snippets/chat_model_tabs.md!}
+{% include-markdown "../../../snippets/chat_model_tabs.md" %}
 
 <!---
 ```python

docs/docs/tutorials/get-started/4-human-in-the-loop.md

@@ -14,7 +14,7 @@ Starting with the existing code from the [Add memory to the chatbot](./3-add-mem
 
 Let's first select a chat model:
 
-{!snippets/chat_model_tabs.md!}
+{% include-markdown "../../../snippets/chat_model_tabs.md" %}
 
 <!---
 ```python
@@ -221,7 +221,7 @@ The input has been received and processed as a tool message. Review this call's
 
 Check out the code snippet below to review the graph from this tutorial:
 
-{!snippets/chat_model_tabs.md!}
+{% include-markdown "../../../snippets/chat_model_tabs.md" %}
 
 ```python
 from typing import Annotated

docs/docs/tutorials/get-started/5-customize-state.md

@@ -221,7 +221,7 @@ Manual state updates will [generate a trace](https://smith.langchain.com/public/
 
 Check out the code snippet below to review the graph from this tutorial:
 
-{!snippets/chat_model_tabs.md!}
+{% include-markdown "../../../snippets/chat_model_tabs.md" %}
 
 <!---
 ```python

docs/docs/tutorials/get-started/6-time-travel.md

@@ -14,7 +14,7 @@ You can create these types of experiences using LangGraph's built-in **time trav
 
 Rewind your graph by fetching a checkpoint using the graph's `get_state_history` method. You can then resume execution at this previous point in time.
 
-{!snippets/chat_model_tabs.md!}
+{% include-markdown "../../../snippets/chat_model_tabs.md" %}
 
 <!---
 ```python