Create devcontainer.json

Please include a description of this change and which issue it fixes. If no issue exists yet please include context and what problem it solves.

[x] Functional review done
[x] Potential edge cases thought about (behavior of the code with strange input, with strange internal state or possible interactions with other Matomo subsystems)
[x] Usability review done (is anything maybe unclear or think about anything that would cause people to reach out to support)
[x] Security review done
[x] Wording review done
[x] Code review done
[x] Tests were added if useful/possible
[x] Reviewed for breaking changes
[x] Developer changelog updated if needed
[x] Documentation added if needed
[x] Existing documentation updated if needed

matomo-org / device-detector