[FEATURE] add an option to generate atoms in whatever namespace i'd like (or none)

[tycobbb]

is your feature request related to a problem? please describe.

i think of the atoms i generate from types in my own project to be conceptually part of my project (and its namespace), rather that part of unity atoms. and i prefer to leave any types in my game's namespace as internal (i.e. omitted, the default access control modifier for types).

when generating atoms, afaict the only option is to generate them in a namespace under UnityAtoms which means that any types i create atoms for have to be made public. this proliferates, as then any types in the now-public-type's public interface must also be made public.

describe the solution you'd like

it'd be nice to specify any namespace for the atoms to be generated (including no namespace), and to be able to specify a similar namespace for the editor files (in case that's different).

describe alternatives you've considered

i could manually edit all the atom files, but that seems to make the generator less practical. also sorry if this is already possible and i'm just missing something obvious.

additional context

this also would solve the type-ambiguity problem when other namespaces contain a conflicting type to the one you're generating atoms for:

using UnityEditor;
using MyGame.Ui;

namespace UnityAtoms.Editor {
    [CustomEditor(typeof(MenuEvent))]                // `Menu` here is ambiguous
    public sealed class MenuEventEditor: AtomEventEditor<Menu, MenuEvent> { }
}

vs.

using UnityEditor;

namespace MyGame.Ui {
    [CustomEditor(typeof(MenuEvent))]                // `Menu` here is `MyGame.Ui.Menu`
    public sealed class MenuEventEditor: AtomEventEditor<Menu, MenuEvent> { }
}