Many files from the `shared` folder were importing files from the `server` folder.
When attempting to use Typescript project references to describe dependencies,
it highlighted a circular dependency beetween `shared` <-> `server`.
The Typescript project forbid such usages.
Using project references greatly improve performance by rebuilding only
the updated project and not all source files.
> see https://www.typescriptlang.org/docs/handbook/project-references.html
Only PeerTube was compatible with it, and the library has moved on
RsaSignature2018 and removed RsaSignature2017 support. We had to create
a dirty fork of the RsaSignature2017 branch, which is not ideal.
Now we use the Mastodon implementation, that most other AP
implementations that support JSONLD signatures use.
It's faster, and will allow us to use RSA signature 2018 (with upstream
jsonld-signature module) without too much incompatibilities in the
peertube federation