Raw output of tasks

**Is your feature request related to a problem? Please describe.**
I think it would be a huge benefit for this cli if we could print out the current tasks in raw json form, so that other projects could migrate it into editors, for example vim or visual studio code.

**Describe the solution you'd like**
I would implement a flag called `raw` changing the output format to a json object with all requested information.

**Additional context**
```sh
$ tb -raw
```
```json
{
"task_name": "Make some food",
"checked": false,
"created": "and so on"
}
```

Start at the CLI entry point handling `tb -raw` and trace how current tasks are assembled and printed. Define the JSON fields needed for all requested task information, then verify that the raw mode emits valid JSON suitable for editor integration while preserving the existing output mode.

Written by the indexing model from the issue text.