feat(event_handler): adding resolve async public API

[leandrodamascena]

Issue number: closes #8137

Changes

Add public resolve_async(event, context) method to ApiGatewayResolver. All resolvers inherit it automatically (APIGatewayRestResolver, APIGatewayHttpResolver, ALBResolver, etc).

User experience

import asyncio                                                                                                                                          
from aws_lambda_powertools.event_handler import APIGatewayHttpResolver                                                                                  
                                                                                                                                                        
app = APIGatewayHttpResolver()                                                                                   
                                                                                                                                                        
@app.get("/dashboard/<user_id>")                                                                                                                        
async def get_dashboard(user_id: str):                                                                                                                  
    orders, profile = await asyncio.gather(                                                                                                             
        get_orders(user_id),                                                                                     
        get_profile(user_id),                                                                                                                           
    )                                                                                                                                                   
    return {"orders": orders, "profile": profile}                                                                                                       
                                                                                                                                                        
def lambda_handler(event, context):                                                                                                                     
    return asyncio.run(app.resolve_async(event, context))

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[sonarqubecloud]

Quality Gate passed

Issues
3 New issues
0 Accepted issues

Measures
0 Security Hotspots
0.0% Coverage on New Code
0.0% Duplication on New Code

See analysis details on SonarQube Cloud

[codecov]

Codecov Report

❌ Patch coverage is 81.25000% with 3 lines in your changes missing coverage. Please review.
✅ Project coverage is 96.70%. Comparing base (3c588e9) to head (ac6f08c).

Files with missing lines	Patch %	Lines
aws_lambda_powertools/event_handler/api_gateway.py	81.25%	2 Missing and 1 partial ⚠️

Additional details and impacted files

@@             Coverage Diff             @@
##           develop    #8171      +/-   ##
===========================================
- Coverage    96.71%   96.70%   -0.02%     
===========================================
  Files          286      286              
  Lines        14325    14341      +16     
  Branches      1197     1200       +3     
===========================================
+ Hits         13855    13868      +13     
- Misses         341      343       +2     
- Partials       129      130       +1     

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