common: download from URL, improve parallel download progress status

[phymbert]

Context

When downloading a sharded model, files are downloaded in parallel, it was added in:

• common: llama_load_model_from_url split support  #6192

The progressions of each download conflict:

Need to properly implement CURLOPT_NOPROGRESS for parallel download.

Example in #6515:

main --hf-repo ggml-org/models \
  --hf-file grok-1/grok-1-q4_0-00001-of-00009.gguf \
  --model   models/grok-1-q4_0-00001-of-00009.gguf \
  -ngl 64
   --prompt "I believe the meaning of life is"

[TevinWang]

Hi! Can I take on this issue as a first contribution?

[phymbert]

Sure, good luck, please ping here for any question

[phymbert]

Hi @TevinWang, are you still working on this issue ?

[TevinWang]

Yes, sorry, still working on it!

[phymbert]

Thanks, no worries, take your time.

[TevinWang]

@phymbert Just created a PR, #6831, let me know if there are any changes needed!