Handle no accept header in the request issue

[shashankbrgowda]

This PR fixes issue when we get requests without any accept header.

Error in prod

2025-09-19 10:33:13.983 | INFO     | logging:callHandlers:1706 - 10.251.245.102:33020 - "GET /rapid/id/GeneID_123505981 HTTP/1.1" 500                                                                                                                                                      
ERROR:    Exception in ASGI application                                                                                                                                                                                                                                                    
Traceback (most recent call last):                                                                                                                                                                                                                                                         
  File "/app/api/resources/rapid_view.py", line 56, in resolve_rapid_stable_id                                                                                                                                                                                                             
    if is_json_request(request):                                                                                                                                                                                                                                                           
       ^^^^^^^^^^^^^^^^^^^^^^^^                                                                                                                                                                                                                                                            
  File "/app/api/utils/commons.py", line 35, in is_json_request                                                                                                                                                                                                                            
    return "application/json" in request.headers.get("accept")                                                                                                                                                                                                                             
           ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^                                                                                                                                                                                                                             
TypeError: argument of type 'NoneType' is not iterable                                                                                                                                                                                                                                     
                                                                                                                                                                                                                                                                                           
During handling of the above exception, another exception occurred:
  File "/app/api/resources/rapid_view.py", line 62, in resolve_rapid_stable_id                                                                                                                                                                                                             
    if is_json_request(request):                                                                                                                                                                                                                                                           
       ^^^^^^^^^^^^^^^^^^^^^^^^                                                                                                                                                                                                                                                            
  File "/app/api/utils/commons.py", line 35, in is_json_request                                                                                                                                                                                                                            
    return "application/json" in request.headers.get("accept")                                                                                                                                                                                                                             
           ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^                                                                                                                                                                                                                             
TypeError: argument of type 'NoneType' is not iterable

Reproduced in local
curl -v -H "Accept:" http://127.0.0.1:8001/rapid/id/XM_027192776.1

Error

  File "/Users/shabr/PythonProjects/ensembl-web-resolver/app/api/resources/rapid_view.py", line 33, in resolve_rapid_stable_id
    if is_json_request(request):
       ^^^^^^^^^^^^^^^^^^^^^^^^
  File "/Users/shabr/PythonProjects/ensembl-web-resolver/app/api/utils/commons.py", line 35, in is_json_request
    return "application/json" in request.headers.get("accept")
           ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
TypeError: argument of type 'NoneType' is not iterable

After fix we should get resolver html error page