rename repo namespace to langchain-ai (#11259)

### Description
renamed several repository links from `hwchase17` to `langchain-ai`.

### Why
I discovered that the README file in the devcontainer contains an old
repository name, so I took the opportunity to rename the old repository
name in all files within the repository, excluding those that do not
require changes.

### Dependencies
none

### Tag maintainer
@baskaryan

### Twitter handle
[kzk_maeda](https://twitter.com/kzk_maeda)