[enhancement] Use enums instead of strings for known errors

[OlegNovosad]

There are plenty of known errors (e.g. UNSUPPORTED for sensors specific events) and using enum would be less error prone for the package users.

[khamidjon-khamidov]

@OlegNovosad I also thought about it but one issue would be we would have to update the library every time new field is added for enum. What do you think?

[OlegNovosad]

We can trysealed classes, e.g.:

sealed class Error {
  final String rawValue;
  
  Error(this.rawValue);
}

class Unsupported extends Error {
  Unsupported() : super("UNSUPPORTED");
}

class Unknown extends Error {
  Unknown(super.rawValue);
}

or NotImplemented, RawError etc.

[khamidjon-khamidov]

Let's say new error is added by Telegram.

Until we introduce the new enum/sealed type, users would check

if (error is Unknown) { 
    error.rawValue
}

Then after we do the update, they would have to change it again accordingly. I would assume this could be done via extensions by users if needed