MFE Plugins: Create slots for the right and left sidebar spaces in the LMS

"As a course administrator, I want to customize my learners' experience as they progress through course content, by customizing the space on either side of the course content."

In the Course Content pages of the LMS, there should be a plugin slot on the left side of the course content and the right side of the course content.

This is a barebones implementation to start, and both slots should be developed as default empty.

The slots should be configurable such that one or multiple plugins can be developed and implemented via the slots. For example, if users want to use the right sidebar space for three plugins - a notifications plugin, an upsell message, and an AI chat bot (just hypothetical examples) - they can implement all three on the sidebar and configure the order in which the plugins appear.

We will decide later on the core platform use of the slots. It is likely that the left sidebar slot will be used for sidebar navigation, and the right sidebar slot will be used for notifications, but TBD.