Order in mapping files

## Bring order to exported mapping files

The feature I would like to see is the order of names in exported mapping to be the same as they are declared in a class.

As I was deobfuscating a .jar and commiting updates to the [mapping file](https://github.com/Deep-0pen/DeepOpen-public/commits/main/Recaf/GoF2/GoF2_JSR_1.0.4.mapping)...

_my routine is:_
1. _load original .jar_
2. _load last mapping_
3. _change names_
4. _export mapping_

...I noticed that order of fileds in exported mapping files changes everytime _(I think only in in scope of Classes that just had any fields or methods mapping edited)._ They shuffle in unknown to me pattern.

PS. Type of mapping (proguard, simlple etc.) doesn't matter they all shuffle.