Authorize with multiple bot IDs

Description

When an app is installed on an organization (for use of Admin APIs) incoming events may have the same bot user ID but different bot IDs. Currently, the authorize callback only allows apps to return a single bot ID as a single string. We could make that type a string | string[] | undefined and update the ignoreSelf middleware to iterate over the array to match events that should be ignored.

const app = new App({
  authorize: async ({ }) => {
    // lookup installations in database ...
    return {
      userToken: 'xoxp-...',
      botToken: 'xoxb-...',
      botId: ['B12345', 'B67890'],
      botUserId: 'W54321',
    };
  },
});

Requirements (place an x in each of the [ ])

• I’ve read and understood the Contributing guidelines and have done my best effort to follow them.
• I’ve read and agree to the Code of Conduct.
• I’ve searched for any related issues and avoided creating a duplicate issue.

[seratch]

@josh91hickman Thanks for taking the time to make the PR! The following comment may affect your PR. 🙏

@aoberoi I revisited this issue and came to think of the possibility to have another field name botIds in the case.

// in the case of workspace-level installation
return {
  userToken: 'xoxp-...',
  botToken: 'xoxb-...',
  botId: 'B12345',
  botUserId: 'W54321',
};

// in the case of org-level installation
return {
  userToken: 'xoxp-...',
  botToken: 'xoxb-...',
  botIds: ['B12345', 'B67890'],
  botUserId: 'W54321',
};

To me, returning either of botId or botIds is more consistent in terms of naming. This means Bolt expects botId for workspace installed apps while it understands the apps is org-level installed one by encountering botIds.

Do you believe we should go with botId for both?

[seratch]

This task is no longer relevant. Let me close it now.