[Http][Kiota] Include Kiota API Client code generation as part of the Uno Kiota Extension

[kazo0]

Along with work from #2510

Currently, the generation of the kiota classes based on the openapi json/yml spec needs to be done manually before building the project.

See: https://learn.microsoft.com/en-us/openapi/kiota/using#client-generation

We need to find a way to incorporate this into the build process when using the Kiota Uno Extension.

Proposed API

I am imagining something like an IHostBuilder extension method called .UseKiota("PATH_TO_API_SPEC.json") or perhaps on a per client basis like:

hostBuilder.UseHttp((context, services) => services
	.AddKiotaClient("PATH_TO_API_SPEC.json")
	.AddKiotaClient("PATH_TO_A_DIFFERENT_API_SPEC.yml")
);