Add ConfigureAwait(false) to all library await calls

[rido-min]

Summary

The library projects under Libraries/ are missing .ConfigureAwait(false) on virtually all await calls (~150+ call sites). As library code that may be consumed in contexts with a SynchronizationContext, this is a best practice to prevent unnecessary context capture and potential deadlocks.

Affected projects

Project	Approximate await sites
Microsoft.Teams.Api	28
Microsoft.Teams.Apps	50+
Microsoft.Teams.Common	9+
Microsoft.Teams.AI	20+
Microsoft.Teams.AI.Models.OpenAI	10+
Microsoft.Teams.Plugins.*	20+
Microsoft.Teams.Extensions.*	5+

Why this matters

• Library code should not capture the caller's synchronization context
• Without ConfigureAwait(false), awaiting a library method from a context with a SynchronizationContext (e.g., ASP.NET on .NET Framework, WPF, WinForms) and then blocking (.Result or .Wait()) causes a deadlock
• Even without deadlocks, unnecessary context switching adds overhead

Suggested fix

Add .ConfigureAwait(false) to every await in library code. This can be enforced with an analyzer like ConfigureAwaitChecker or the built-in CA2007 rule.

Example:

// Before
var res = await _http.SendAsync(req, cancellationToken);

// After
var res = await _http.SendAsync(req, cancellationToken).ConfigureAwait(false);