Fix from langchain_core.load.load import load import (#30843)

TL;DR: you can't optimize imports with a lazy `__getattr__` if there is
a namespace conflict with a module name and an attribute name. We should
avoid introducing conflicts like this in the future.

This PR fixes a bug introduced by my lazy imports PR:
https://github.com/langchain-ai/langchain/pull/30769.

In `langchain_core`, we have utilities for loading and dumping data.
Unfortunately, one of those utilities is a `load` function, located in
`langchain_core/load/load.py`. To make this function more visible, we
make it accessible at the top level `langchain_core.load` module via
importing the function in `langchain_core/load/__init__.py`.

So, either of these imports should work:

```py
from langchain_core.load import load
from langchain_core.load.load import load
```

As you can tell, this is already a bit confusing. You'd think that the
first import would produce the module `load`, but because of the
`__init__.py` shortcut, both produce the function `load`.

<details> More on why the lazy imports PR broke this support...

All was well, except when the absolute import was run first, see the
last snippet:

```
>>> from langchain_core.load import load
>>> load
<function load at 0x101c320c0>
```

```
>>> from langchain_core.load.load import load
>>> load
<function load at 0x1069360c0>
```

```
>>> from langchain_core.load import load
>>> load
<function load at 0x10692e0c0>
>>> from langchain_core.load.load import load
>>> load
<function load at 0x10692e0c0>
```

```
>>> from langchain_core.load.load import load
>>> load
<function load at 0x101e2e0c0>
>>> from langchain_core.load import load
>>> load
<module 'langchain_core.load.load' from '/Users/sydney_runkle/oss/langchain/libs/core/langchain_core/load/load.py'>
```

In this case, the function `load` wasn't stored in the globals cache for
the `langchain_core.load` module (by the lazy import logic), so Python
defers to a module import.

</details>

New `langchain` tongue twister 😜: we've created a problem for ourselves
because you have to load the load function from the load file in the
load module 😨.

libs/core/langchain_core/load/__init__.py

@@ -5,9 +5,15 @@ from typing import TYPE_CHECKING
 
 if TYPE_CHECKING:
     from langchain_core.load.dump import dumpd, dumps
-    from langchain_core.load.load import load, loads
+    from langchain_core.load.load import loads
     from langchain_core.load.serializable import Serializable
 
+# Unfortunately, we have to eagerly import load from langchain_core/load/load.py
+# eagerly to avoid a namespace conflict. We want users to still be able to use
+# `from langchain_core.load import load` to get the load function, but
+# the `from langchain_core.load.load import load` absolute import should also work.
+from langchain_core.load.load import load
+
 __all__ = ["dumpd", "dumps", "load", "loads", "Serializable"]
 
 _dynamic_imports = {