Usage of the file query parameter

# Question

CodeCharta allows to directly load a cc.json file from the url (e.g. the web version uses this to load two maps: https://maibornwolff.github.io/codecharta/visualization/app/?file=codecharta.cc.json.gz&file=codecharta_analysis.cc.json.gz). This currently requires that one is hosting the cc.json files themselves. This has been a feature since 2018 but is not documented well.
We recently added a feature, that the different metrics can be set in the url, given the url contains a file. This can be great to share the view of a map but only works if one is hosting their cc.json files somewhere, which not many users will do.

### Questions:
What was the original purpose of the file query parameter and can we use this to make maps more easily sharable?

## Preparation

Please check these resources first before posting a question

* [ ] I searched for answers in [older issues](https://github.com/MaibornWolff/codecharta/issues?utf8=%E2%9C%93&q=)
* [ ] I looked into the [README.md](https://github.com/MaibornWolff/codecharta)
* [ ] I read the [website](https://maibornwolff.github.io/codecharta/)

Read README.md and the website, then inspect the visualization app's existing handling of the file query parameter. Use the linked web-version URL as a concrete example and review older issues for context. Done means documenting the parameter's original purpose and determining whether it can support more easily shareable maps.

Written by the indexing model from the issue text.