Allow enable/disable page telemetry (e.g. load events)

[waltjones]

Description of the change

This PR adds a telemetry enable/disable flag for "page" events. This currently applies to load and DOMContentLoaded events. In the current SDK, these listeners are only added in the snippet, therefore this change is for the snippet only.

In keeping with other telemetry flags, the feature defaults to enabled when the flag isn't present. Set false to disable.

Usage:

      var _rollbarConfig = {
        accessToken: "POST_CLIENT_ITEM_TOKEN",
        autoInstrument: {
          page: false
        }
      };

Notes:
The affected events were previously controlled by the network flag. This flag is unnecessarily broad, and disabling also disables all network telemetry (XHR, fetch, etc.) Additionally, the load events aren't directly network related.

This PR includes the rebuilt snippet.

Type of change

• Bug fix (non-breaking change that fixes an issue)

Related issues

Fixes https://app.shortcut.com/rollbar/story/109193/

Development

• Lint rules pass locally
• The code changed/added as part of this pull request has been covered with tests
• All tests related to the changed code pass in development

Code review

• This pull request has a descriptive title and information useful to a reviewer. There may be a screenshot or screencast attached
• "Ready for review" label attached to the PR and reviewers assigned
• Issue from task tracker has a link to this pull request
• Changes have been reviewed by at least one other engineer

[mudetroit]

LGTM