Improve HttpRequestBuilder fluent API, retries, and per-request logging

[mr-kg]

Improve HttpRequestBuilder fluent API, retries, and per-request logging

Summary

This PR expands HttpRequestBuilder into a more complete fluent request builder while keeping the existing Add* methods available for compatibility.

The main additions are:

• Polly retry support via WithRetry(...)
• URI constructor and WithUri(...)
• no-URI HTTP verb overloads, plus Patch, Head, and Options
• retry-safe HttpContent factories
• per-request headers, authorization, cancellation, body, JSON serializer settings, and logging helpers
• per-request ILogger support with WithLogger(...) and optional WithLogScope(...)

Notable Changes

Fluent API

• Added HttpRequestBuilder(string uri)
• Added WithUri(string uri)
• Added no-URI overloads for Get, Post, Put, Patch, and Delete
• Added Patch, Head, and Options verb methods
• Added WithBody, WithContent, WithHeader, WithBearerToken, WithAuthorization, WithCancellationToken, and WithJsonSerializerSettings

Retry Support

• Added Polly package dependency
• Added WithRetry(ResiliencePipeline<Response>)
• Retry policies work for both MakeRequestAsync() and MakeRequestAsync<T>()
• Added WithContent(Func<HttpContent>) / AddContent(Func<HttpContent>) so retries can create fresh request content per attempt

Logging

• Added per-request WithLogger(ILogger logger)
• Added per-request WithLogScope(Enums.LogScope logScope)
• WithLogger(...) defaults to logging all request activity
• WithLogScope(Enums.LogScope.OnlyFailedRequests) limits that request to failed response logging
• Per-request logger config overrides global HttpConfig.Logger for that request

Request Handling

• HttpResponseMessage is now disposed after response materialization
• Header values now replace existing values instead of throwing on duplicate keys
• Authorization is routed through typed AuthenticationHeaderValue handling
• Query/form parameters now allow duplicate keys instead of silently ignoring later values
• AddQueryParams now accepts IEnumerable<KeyValuePair<string, string>>

Documentation

• README updated with examples for:
  • constructor URI usage
  • WithUri
  • Patch
  • Head / Options
  • retry with Polly
  • retry-safe content factories
  • per-request logging
  • serializer settings
  • single-use builder guidance

Compatibility Notes

Existing builder methods such as AddBody, AddHeader, AddContent, and AddCancellationToken remain available. They now delegate to the newer With* methods where appropriate.

The behavior of duplicate query/form parameters changed: duplicate keys are now preserved. This better matches common HTTP query string behavior, but it is worth calling out for consumers who relied on duplicate suppression.

Tests

Ran:

dotnet test

Result:

Passed! - Failed: 0, Passed: 52, Skipped: 0