Sort error codes within their categories when printing with `plc config diagnostics`

[mhasel]

Is your feature request related to a problem? Please describe. Currently, if you want to see the error severity configuration and print it via plc config diagnostics, the error codes will be in a random order within their respective severity. If you then write the output to a json file, it will look something like this:

{
    "warning": [
        "E013",
        "E022",
        "E047",
        "E014",
        "E015",
        "E090",
        "E004",
        "E042",
        "E023",
        "E049",
        "E091",
        "E039",
        "E093",
        "E024",
        "E016"
    ],

    ...
}

Describe the solution you'd like Sort the error codes in their categories ascendingly, to make it easier to find the codes you are looking for.

[ghaith]

In addittion, we should use the json pretty_print or to_string_pretty method here so that the json is pormatted without needing to pipe it to a formatter.