Feature/Add Confluence Document Loader

[neerajkrbansal1996]

Issue:
#222

Results

[CLAassistant]

All committers have signed the CLA.

[HenryHengZJ]

Looks good! Thanks @neerajkrbansal1996 !

[mrkhachaturov]

There is no support for data center/server version where personal token is used.

Personal Access Token (Server/On-Prem only)
This method is valid for the Data Center/Server on-prem edition only. For more information on how to generate a Personal Access Token (PAT) check the official Confluence documentation at: https://confluence.atlassian.com/enterprise/using-personal-access-tokens-1026032365.html. When using a PAT you provide only the token value, you cannot provide a username. Please note that ConfluenceLoader will run under the permissions of the user that generated the PAT and will only be able to load documents for which said user has access to.

`import { ConfluencePagesLoader } from "langchain/document_loaders/web/confluence";

const username = process.env.CONFLUENCE_USERNAME;
const accessToken = process.env.CONFLUENCE_ACCESS_TOKEN;
const personalAccessToken = process.env.CONFLUENCE_PAT;

if (username && accessToken) {
  const loader = new ConfluencePagesLoader({
    baseUrl: "https://example.atlassian.net/wiki",
    spaceKey: "~EXAMPLE362906de5d343d49dcdbae5dEXAMPLE",
    username,
    accessToken,
  });

  const documents = await loader.load();
  console.log(documents);
} else if (personalAccessToken) {
  const loader = new ConfluencePagesLoader({
    baseUrl: "https://example.atlassian.net/wiki",
    spaceKey: "~EXAMPLE362906de5d343d49dcdbae5dEXAMPLE",
    personalAccessToken,
  });
  const documents = await loader.load();
  console.log(documents);
} else {
  console.log(
    "You need either a username and access token, or a personal access token (PAT), to use this example."
  );
}`