Correctly interpret string arguments as booleans in electron arguments.

[MichaelMauderer]

Pull Request Description

Previously arguments were passed to the main function as strings when using the electron app, or as booleans when using the development environment. Since false is a truthy value that was not further checked, this lead to wrong settings.
This PR adds a conversion of true and false to their boolean values, and adds an assertion that ensures that arguments are actually booleans.

Important Notes

Converts content/index.js to typescript.

Checklist

Please include the following checklist in your PR:

• The CHANGELOG.md was updated with the changes introduced in this PR.
• The documentation has been updated if necessary.
• All code conforms to the Rust style guide.
• All code has automatic tests where possible.
• All code has been profiled where possible.
• All code has been manually tested in the IDE.
• All code has been manually tested in the "debug/interface" scene.
• All code has been manually tested by the PR owner against our test scenarios.
• All code has been manually tested by at least one reviewer against our test scenarios.

[wdanilo]

A lot has changed here, especialy after moving to TypeScript. Im ok with all the changes, but I've got a question and request:

1. I understand that it is formatted with prettier?
2. Please triple check that everything works and there are not regressions with mixpanel etc.