Remove global mediator commands from Web IDE

MR: Pending

Description

This is a follow up issue to remove remaining mediator command relevant code that utilizes cookie-based execution of HTTP requests.

Stems from the following discussion from !474 (merged):

@ealcantara: I think this MR's scope is very good to unblock the VSCode Fork update. Looking at the bigger picture, I think that we could simplify the codebase significantly by removing all the code related to supporting the cookie-based execution of HTTP requests.

I spent some time reading the mediator command source files and I estimate that it's gonna take several merge requests to clean up the codebase. It's not urgent though. We can resume this clean up once we need to do it or we have bandwidth.

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