Apache-2 license headers

[aasseman]

The license requires headers at the top of each source file.

I propose that we use this format:

// Copyright 2023-, [attribution]
// SPDX-License-Identifier: Apache-2.0

However, I'm not 100% sure about the attribution. Should it be "Hope Yen", "GraphOps", "GraphOps and Semiotic Labs", "The Graph Foundation"? Perhaps it could also be per file, such that files that I creates have "Alexis Asseman", and yours are "Hope Yen"?

And then we can also use CI like here to make sure we don't forget in the future?

[hopeyen]

"GraphOps and Semiotic Labs" may be a good level of specification although the name is quite long (we can't exactly use Ops&Labs). maybe "The Graph Core Devs"?
The CI looks good, I'm fine with anything you pick!