core[minor]: Image prompt template (#14263)
Builds on Bagatur's (#13227). See unit test for example usage (below)
```python
def test_chat_tmpl_from_messages_multipart_image() -> None:
base64_image = "abcd123"
other_base64_image = "abcd123"
template = ChatPromptTemplate.from_messages(
[
("system", "You are an AI assistant named {name}."),
(
"human",
[
{"type": "text", "text": "What's in this image?"},
# OAI supports all these structures today
{
"type": "image_url",
"image_url": "data:image/jpeg;base64,{my_image}",
},
{
"type": "image_url",
"image_url": {"url": "data:image/jpeg;base64,{my_image}"},
},
{"type": "image_url", "image_url": "{my_other_image}"},
{
"type": "image_url",
"image_url": {"url": "{my_other_image}", "detail": "medium"},
},
{
"type": "image_url",
"image_url": {"url": "https://www.langchain.com/image.png"},
},
{
"type": "image_url",
"image_url": {"url": "data:image/jpeg;base64,foobar"},
},
],
),
]
)
messages = template.format_messages(
name="R2D2", my_image=base64_image, my_other_image=other_base64_image
)
expected = [
SystemMessage(content="You are an AI assistant named R2D2."),
HumanMessage(
content=[
{"type": "text", "text": "What's in this image?"},
{
"type": "image_url",
"image_url": {"url": f"data:image/jpeg;base64,{base64_image}"},
},
{
"type": "image_url",
"image_url": {
"url": f"data:image/jpeg;base64,{other_base64_image}"
},
},
{
"type": "image_url",
"image_url": {"url": f"{other_base64_image}"},
},
{
"type": "image_url",
"image_url": {
"url": f"{other_base64_image}",
"detail": "medium",
},
},
{
"type": "image_url",
"image_url": {"url": "https://www.langchain.com/image.png"},
},
{
"type": "image_url",
"image_url": {"url": "data:image/jpeg;base64,foobar"},
},
]
),
]
assert messages == expected
```
---------
Co-authored-by: Bagatur <baskaryan@gmail.com>
Co-authored-by: Brace Sproul <braceasproul@gmail.com>
