Add license file and copyright text in each file

[sadiqkhoja]

Before we make this public, we need to add LICENSE file and optionally copyright text in each source file.

[lognaturel]

@yanokwa I believe we've agreed on matching our other projects and using Apache2, right? We believe there's a lot of potential in this being a useful component and want to continue the ODK tradition of being open and creating public goods.

My preference would be to omit the copyright text in each source file. getodk/governance#2 has some ancient discussion around that topic. It's unclear what rights we have to change them once they are there but we can choose not to include them for this project. I really don't think it's realistic for single source files or even a chunk of them to be imported into another project. And if it happens, it's the importer's responsibility to include the license in the most appropriate way for their project.

[yanokwa]

Yes, we are using Apache. Let's add a LICENSE.md with this text https://raw.githubusercontent.com/getodk/central/master/LICENSE.md and the following change.

Copyright 2023-2024 Get ODK Inc

I agree that we don't want to add copyright to each source file.