Create a common mock for CodeEditor

[sabarasaba]

Our team is in the process of replacing the Ace editor in our management apps with Kibana's CodeEditor, this effort is being tracked with #107215. While working on this we found ourselves needing to very often have to mock the editor (and other apps that use monaco tend to do the same thing). I was wondering if perhaps we could have this mock defined somwhere near the CodeEditor itself and consumers can just import the mock when needed

[elasticmachine]

Pinging @elastic/appex-sharedux (Team:SharedUX)