feat(host): add middleware registration tracking with unique identifiers

[j-d-ha]

Summary

Add a mechanism to track registered middleware by unique identifiers (ID or name), allowing users to check if a middleware has already been registered and enabling flexible ordering of middleware registration.

Problem Statement

Currently, middleware is registered in a fixed order without any mechanism to identify already-registered middleware. This prevents users from:

• Checking if a specific middleware is already in the pipeline
• Adding middleware out of the recommended order
• Conditionally registering middleware based on what's already registered

Proposed Solution

Implement a middleware registration tracking system that:

1. Generates unique identifiers for each registered middleware (based on type name or custom identifier)
2. Tracks registered middleware - maintains a collection of registered middleware IDs/names
3. Provides query methods - allows users to check if specific middleware has been registered
4. Supports optional conflicts - can warn or prevent duplicate registrations if needed
5. Documents the feature - provides clear guidance on usage and best practices

Implementation Details

Core Changes

• Add a middleware registry/tracker to ILambdaInvocationBuilder
• Extend middleware registration methods to support ID assignment
• Create utility methods for checking if middleware is registered

API Design

Proposed extension methods:

// Check if middleware by ID is registered
bool IsMiddlewareRegistered(string middlewareId);

// Get list of registered middleware IDs
IReadOnlyList<string> GetRegisteredMiddleware();

// Register middleware with explicit ID
ILambdaInvocationBuilder UseMiddleware(
    string middlewareId, 
    Func<ILambdaHostContext, LambdaInvocationDelegate, Task> middleware
);

// Register middleware with auto-generated ID (e.g., from delegate type)
ILambdaInvocationBuilder UseMiddleware(
    Func<ILambdaHostContext, LambdaInvocationDelegate, Task> middleware
);

Middleware ID Generation

• For inline delegates: Generate ID from delegate method name or provide explicit ID
• For extension methods (e.g., UseClearLambdaOutputFormatting()): Use method name as ID prefix
• Allow explicit ID override for custom middleware

Example Usage

var app = new LambdaApplication(host);

// Register with explicit ID
app.UseMiddleware("ClearLambdaOutputFormatting", async (ctx, next) => { /* ... */ });

// Check if middleware is registered
if (!app.IsMiddlewareRegistered("ClearLambdaOutputFormatting"))
{
    app.UseClearLambdaOutputFormatting();
}

// User can now add middleware in custom order
app.UseMiddleware(async (ctx, next) => { /* custom middleware */ });

Benefits

• Enables conditional middleware registration
• Supports flexible middleware ordering
• Prevents accidental duplicate registrations
• Improves debugging with middleware visibility
• Facilitates middleware discovery

Related Issues

None

Type of Change

• New feature
• Breaking change
• Requires documentation updates
• Requires migration guide

Testing Considerations

• Unit tests for middleware registry operations
• Tests for ID generation and collision handling
• Tests for ordering independence
• Integration tests with existing middleware setup