Make `FunctionStartTimeoutInSeconds` (and related HTTP-coordinator time-outs) configurable

[koudaiii]

Description

Why

Please make time-out parameters such as FunctionStartTimeoutInSeconds configurable so that functions can run in environments where longer startup delays are acceptable.

What

The FunctionStartTimeoutInSeconds is hard-coded to 15 seconds, and the same applies to HttpContextTimeoutInSeconds and FunctionContextTimeoutInSeconds.
If startup might exceed these fixed values due to factors like resource constraints or machine specifications, then these constants may be too strict for environments where longer wait times are acceptable.

The following constants are hard-coded:

        private const int HttpContextTimeoutInSeconds = 5;
        private const int FunctionContextTimeoutInSeconds = 5;
        private const int FunctionStartTimeoutInSeconds = 15;

If the FunctionStartTimeoutInSeconds limit is exceeded, the function fails with a timeout error.

An example message is as follows:

Timed out waiting for the function start call. Invocation: '{invocationId}'. ref

azure-functions-dotnet-worker/extensions/Worker.Extensions.Http.AspNetCore/src/Coordinator/DefaultHttpCoordinator.cs

Line 55 in cf01781

_ = await contextRef.FunctionStartTask.Task.WaitAsync(TimeSpan.FromSeconds(FunctionStartTimeoutInSeconds));

Here is a sample log from a real occurrence:

Timestamp : 5/1/2025 9:06:54 AM
Inner Exception Type: Microsoft.Azure.WebJobs.Script.Workers.Rpc.RpcException
Total Occurrences: 18
Latest Exception Message: Result
/Failure Exception
/Timed out waiting for the function start call. Invocation
/'2ff4f8fd-19ad-4bf9-b5bf-11cf141fe334'.
/
Microsoft.Azure.Functions.Worker.Extensions.Http.AspNetCore.DefaultHttpCoordinator.SetFunctionContextAsync(String invocationId, FunctionContext context) in D:\a\_work\1\s\extensions\Worker.Extensions.Http.AspNetCore\src\Coordinator\DefaultHttpCoordinator.cs:line 67
Microsoft.Azure.Functions.Worker.Extensions.Http.AspNetCore.FunctionsHttpProxyingMiddleware.Invoke(FunctionContext context, FunctionExecutionDelegate next) in D:\a\_work\1\s\extensions\Worker.Extensions.Http.AspNetCore\src\FunctionsMiddleware\FunctionsHttpProxyingMiddleware.cs:line 45
... (stack trace truncated) ...

I would like to request that time-out parameters such as FunctionStartTimeoutInSeconds be made configurable—within reasonable upper and lower bounds—so that they can accommodate environments where longer wait times are acceptable.