[tus] Support Upload-Defer-Length header

[dschmidt]

Is your feature request related to a problem? Please describe.

Uppy Companion turned on the defer length option in tus uploads in transloadit/uppy#4697
oCIS does not support that and hence uploads are broken with the current release of Companion (used in the Importer App)

Describe the solution you'd like

Implement https://tus.io/protocols/resumable-upload#upload-defer-length

Describe alternatives you've considered

Do not implement it and convince the Uppy team to make it optional (or directly send a PR).
transloadit/uppy#5560

Testing

I'm preparing update PRs for oC Web and Web Extensions, that will allow testing the feature somewhat easily ... (imports simply fail with 412 Precondition Failed, visible in the Companion log)