Feature/improve vcl hash

[toonvd]

Description

This PR is a rework of the Magento VCL (the vcl_hash part) PR found here:
https://github.com/magento/magento2/pull/36796/files

It is mildly adapted since I decided to not remove the hashing on the graphql part.

PRs for other subroutines will follow (probably weekly)

All credits go to @peterjaap and @ThijsFeryn, I am simpling slicing this up and removing controversial parts to get early approval.

Related Pull Requests

#62

Manual testing scenarios

• Load the new VCL
• Test if Graphql behaves the same way when authenticated and not authenticated (storeswitch / currencyswitch)

Contribution checklist (*)

• Pull request has a meaningful description of its purpose
• All commits are accompanied by meaningful commit messages
• All new or changed code is covered with unit/integration tests (if applicable)
• README.md files for modified modules are updated and included in the pull request if any README.md predefined sections require an update
• All automated tests passed successfully (all builds are green)

[toonvd]

@danslo I haven't worked with Magento graphQL much, would you be willing to also test / doublecheck?
The changes aren't extreme but I don't want to risk anything.