feat: Support multi-part uploads in JS API

[lucaas]

Resolves FT-cbc1aaec-2dcb-40a5-a298-4d85ea15851e

• I have added automatic tests where applicable
• The PR title is suitable as a release note
• The PR contains a description of what has been changed
• The description contains manual test instructions

Changes

• Moves uploading functionality to a Uploader class to handle both single-part and multi-part uploads
• Implements multi-part uploading (requires support in backend, added in 4.12.0.current.17)
• Retries failed uploads using an exponential back-off.
• This client behaved differently from the Python client and server, which marks the component as being in the location when data transfer is finished and then emits a component-added event.
  • Move creating ComponentLocation to after upload finishes.
  • Emit a component-added event.

Test

• Look through implementation and see if you have any high-level concerns about API or code
• Test together with ftrack-server @ 4.12.0.current.17
• Test with frontend @ https://github.com/ftrackhq/frontend/pull/714
• Test with ftrack-server @ https://github.com/ftrackhq/ftrack-server/pull/351

[gismya]

Seems like a great start. Some inconsistencies in the async syntax used, I suggest making sure async/await is used consistently.

[gismya]

Intuitively, this feels short. Did you base this on anything?

[lucaas]

I've replaced this with a separate implementation in back_off.

It will wait a delay of 0.5s, then double that for each attempt up to a maximum of 64 seconds. It will attempt a maximum of 16 tries before giving up.