Add Apache licenses to header on all our files and update the top level license file

[arosien]

https://github.com/sbt/sbt-header can be used to do this automatically to Scala files, and possibly as a build check during CI.

[arosien]

Also need to replace the existing, incorrect LICENSE.txt with Apache 2.0. Use this issue, or have a separate one?

[arosien]

https://github.com/sbt/sbt-header can be used to do this automatically to Scala files, and possibly as a build check during CI.

I can do this part quick.

[jw3]

Sounds good. Yeah just do all Apache 2.0 licenses in this one.

[arosien]

Who should the copyright be listed as? The real names of @jw3, @arosien? (I think we two were the only Scala contributors.)

[arosien]

https://github.com/jw3/example-daffodil-vscode/tree/issue/126-licenses-for-scala-files

[jw3]

For the ts files https://yarnpkg.com/package/license-check https://github.com/awjh/license-check-and-add

... but doesnt appear to be quite as convenient as it could be.

[jw3]

https://www.apache.org/legal/src-headers.html#headers

[jw3]

Updated all the typescript files to have similar header as the scala files, with addition of @Shanedell

[jw3]

Added a txt file for the snippets json. Read on stack exchange that would be a way to go about that in a non-commentable file

https://opensource.stackexchange.com/a/203