[device_info_plus] deprecate "toMap" method

[iapicca]

Plugin

device_info_plus

Suggestion

the current implementation of toMap output an invalid json
see discussion in this issue and PR
a suggested solution is to deprecate "toMap" in it's entirety

[miquelbeltran]

Thanks, I am in favor of doing this, but I'd like more input from the community and other maintainers before moving forward.

toMap doesn't seem to be used internally, but rather as complement to fromMap, which is used to parse the data passed from native code.

There are some places where the docs are misleading, e.g. in BaseDeviceInfo the comments say:

 /// Serializes device info properties to a map.
 Map<String, dynamic> toMap();

Which is not correct because the output is not serializable.

Since this would mean removing the method, I'd also like to know if we should offer other alternatives. e.g. a toString method and an equals method (simply code-generated)