Fix: loading the document requires knowing the format in advance

[Maggie Kimani (MaggieKimani1)]

This PR:

• Adds logic for inspecting the first character of the stream we receive during document loading to know whether its in JSON or YAML. This helps avoid a regression in functionality where users are required to pass the format of the document when loading an OpenAPI document
• Replaces sync methods with async ones to prevent deadlocks
• Passes a cancellation token to OpenApiModelFactory.GetStreamAsync to allow for cancellation of tasks/requests
• Updates tests with new loading pattern

Fixes#1917, #1918

[Vincent Biret (baywet)]

Thanks for getting this started.
A couple of remarks

[sonarqubecloud]

Quality Gate failed

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[Vincent Biret (baywet)]

why are we adding the task run here?

[Maggie Kimani (MaggieKimani1)]

The caller is async here

OpenAPI.NET/src/Microsoft.OpenApi/Reader/OpenApiModelFactory.cs

Line 147 in f07ff44

publicstaticasyncTask<ReadFragmentResult<T>>LoadAsync<T>(Streaminput,

And the interface method's equivalent in the JsonReader class is also async

OpenAPI.NET/src/Microsoft.OpenApi/Reader/OpenApiJsonReader.cs

Line 124 in f07ff44

publicasyncTask<ReadFragmentResult<T>>ReadFragmentAsync<T>(TextReaderinput,

If I change this method's signature to be synchronous, I'll also need to update this JSON content to be read synchronously:

OpenAPI.NET/src/Microsoft.OpenApi/Reader/OpenApiJsonReader.cs

Line 189 in f07ff44

varcontent=awaitinput.ReadToEndAsync();

[Maggie Kimani (MaggieKimani1)]

Vincent Biret (@baywet) just a head's up, the functionality on inspecting the input stream to determine the format might change based on my discussion with Darrel (@darrelmiller) here #1918 (comment)

[Vincent Biret (baywet)]

Maggie Kimani (@MaggieKimani1) are we going to implement those changes in this PR or in a subsequent one?

[Maggie Kimani (MaggieKimani1)]

Maggie Kimani (@MaggieKimani1) are we going to implement those changes in this PR or in a subsequent one?

I can implement it here so as not to lose the other changes on moving to async