feat(hidden-window): enable baseEnvironment in the pre-request scripting [INS-3379]

[ihexxa]

Changes:

• : enable base environment in pre-request scripting
• : make base environment modification work in rendering
• : add tests for cover it

[filfreire]

LGTM, only has one problem where maybe base environment should not override what we send on the pre-request

insomnia.baseEnvironment.set("testfilipe", "filipe")
pm.collectionVariables.set("testfilipe", "george")

[gatzjames]

We should also test environment overrides on the folder level.
If you put a request inside a folder, the folder has an option to add environment overrides that override environment variables

[ihexxa]

Thank you for comments! The overriding issue is fixed.
Regarding folder environments, this is a really good point. The workflow might be a bit not intuitive: currently scripts mainly manipulates environment from "collection" level, although script is at request level. Then script's environment modifications will be overridden by folder environments. When the per-request variables are introduced, it can also be manipulated by script, which will override folder environments.