[Feature]: Widgets should have option for fixed width

### Is there an existing issue for this?

- [X] I have searched the existing issues

### Summary

A user reached out to us for this feature request. They wanted to have some of the containers even when `Fluid Width` is selected for Canvas Size.

### Why should this be worked on?

User request [link](https://app.intercom.com/a/inbox/y10e7138/inbox/shared/all/conversation/164629100159317)