fix: Argilla not working behind proxy

[gabrielmbmb]

Description

This PR updates the URL in which the Argilla App is mounted to be "/", as it's not required to change the URL of the server because the proxy will know what rewrite has to be done.

In addition, the entrypoint scripts of both images have been updated to add the --root-path $ARGILLA_BASE_URL option to the uvicorn command if ARGILLA_BASE_URL env variable has been set. More info: FastAPI - Behind a proxy.

Closes #3542

Type of change

• Bug fix (non-breaking change which fixes an issue)

How Has This Been Tested

• localhost/argilla load in a web browser and can connect using rg.init with an NGINX local setup:

  Local Nginx

  docker-compose.yaml:

  version: '3.8'
  
  services:
  argilla:
    image: argilla/argilla-quickstart:pr-3543
    environment:
      ARGILLA_BASE_URL: /argilla
      LOAD_DATASETS: none
    ports:
      - 6900:6900
  
  nginx:
    image: nginx:latest
    ports:
      - 80:80
    volumes:
      - ./nginx.conf:/etc/nginx/nginx.conf

  nginx.conf:

  events {}
  
  http {
  server {
      listen 80;
  
      server_name your_server_name_or_ip;
  
      location /argilla/ {
          proxy_pass http://argilla:6900/;
          proxy_set_header Host $host;
          proxy_set_header X-Real-IP $remote_addr;
          proxy_set_header X-Forwarded-For $proxy_add_x_forwarded_for;
          proxy_set_header X-Forwarded-Proto $scheme;
      }
  }
  }
  

Checklist

• I followed the style guidelines of this project
• I did a self-review of my code
• My changes generate no new warnings
• I have added tests that prove my fix is effective or that my feature works
• I filled out the contributor form (see text above)
• I have added relevant notes to the CHANGELOG.md file (See https://keepachangelog.com/)

[codecov]

Codecov Report

Patch coverage: 100.00% and project coverage change: -0.08% ⚠️

Comparison is base (3225258) 90.49% compared to head (8ea8533) 90.41%.
Report is 2 commits behind head on releases/1.14.0.

Additional details and impacted files

@@                 Coverage Diff                 @@
##           releases/1.14.0    #3543      +/-   ##
===================================================
- Coverage            90.49%   90.41%   -0.08%     
===================================================
  Files                  254      254              
  Lines                13534    13534              
===================================================
- Hits                 12247    12237      -10     
- Misses                1287     1297      +10     

Files Changed	Coverage Δ
src/argilla/server/server.py	86.50% <100.00%> (ø)

... and 2 files with indirect coverage changes

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