Fill copyright field in .csproj files to ensure that nuget packages will have both license and copyright fields filled

[Konstantin-Kretov]

Since Godot uses the MIT license, copyright is important for the correct display of license information.
This pull request adds the copyright to the csproj files, from where it will then go into NuGet packages.
The value from the LICENSE.txt file in the root of the repository was used as the copyright:

Copyright (c) 2014-present Godot Engine contributors (see AUTHORS.md).
Copyright (c) 2007-2014 Juan Linietsky, Ariel Manzur.

[akien-mga]

Looks good to me from a copyright/license point of view.
No idea about the .NET ecosystem integration, I'll let the team assess.

[akien-mga]

Since I assume AUTHORS.md won't be shipped together with the nuget package, I think we can change it to just:

Suggested change

	<Copyright>Copyright (c) 2014-present Godot Engine contributors (see AUTHORS.md).
	<Copyright>Copyright (c) 2014-present Godot Engine contributors.

That's what we do e.g. for in-engine copyright statements.

[raulsntos]

Makes sense to me although I'm not sure how I feel about using multiple-lines. Microsoft's documentation recommends the format Copyright (c) <name/company> <year>. although they don't seem to follow this format in their own packages:

https://github.com/dotnet/arcade/blob/d54f6057363b8b249be56dcf8b91aa847f97a904/src/Microsoft.DotNet.Arcade.Sdk/tools/ProjectDefaults.props#L11-L12

@akien-mga How about just including Copyright (c) Godot Engine contributors to keep it short and a single line?

[akien-mga]

How about just including Copyright (c) Godot Engine contributors to keep it short and a single line?

Sounds good to me.

[Konstantin-Kretov]

@raulsntos I am not sure if we should remove personal mentions of the 2007-2014 contributors.
If you want to have a single line copyright, I would suggest:
Copyright (c) 2007-2014 Juan Linietsky, Ariel Manzur, 2014-present Godot Engine contributors.

[akien-mga]

Technically there's not much code from Juan and Ariel in the GodotSharp packages, so it's fine to just make it a blanket statement for all contributors.

Note: I'm the main "copyright" guy so you can trust my decision on that ;) Juan and Ariel won't feel left out.

[Konstantin-Kretov]

@akien-mga So, the final decision is Copyright (c) Godot Engine contributors right?

[Konstantin-Kretov]

@akien-mga I have just updated the files as we agreed.

[akien-mga]

Looks good! Could you squash the commits? See PR workflow for instructions.

[Konstantin-Kretov]

Done

[akien-mga]

Last nitpick, could you amend the commit message to be more like this:

Fill copyright field in .csproj files

This ensures that nuget packages will have both license and copyright fields filled.

It's best not to put user mentions in commits, as this generates a notification every time you or someone else re-pushes this commit, amended or as is.

Commit messages should also have a short title, otherwise it gets truncated and wrapped into a "more" field, as seen here:

[Konstantin-Kretov]

Done. I'm sorry to bother you so much.

[akien-mga]

No worry! We're somewhat opinionated around the Git history in the Godot repo :D

[akien-mga]

Thanks! And congrats for your first merged Godot contribution 🎉