Remove WebHost usage

[martincostello]

Remove long-deprecated WebHost usage and instead use Host.

Flushed out by trying to use WebApplicationFactory<T> for Redoc with #3516.

[Copilot]

Pull Request Overview

Modernizes ASP.NET Core hosting by replacing deprecated WebHost with the current Host pattern across test websites and CLI tools.

• Updates from WebHost.CreateDefaultBuilder() to Host.CreateDefaultBuilder().ConfigureWebHostDefaults()
• Standardizes method names from various patterns to CreateHostBuilder
• Removes unnecessary Microsoft.AspNetCore using statements

Reviewed Changes

Copilot reviewed 5 out of 5 changed files in this pull request and generated no comments.

Show a summary per file

File	Description
test/WebSites/TestFirst/Program.cs	Updates hosting pattern and renames method from CreateWebHostBuilder to CreateHostBuilder
test/WebSites/ReDoc/Program.cs	Updates hosting pattern and renames method from BuildWebHost to CreateHostBuilder
test/WebSites/ConfigFromFile/Program.cs	Updates hosting pattern and renames method from BuildWebHost to CreateHostBuilder
test/WebSites/CliExample/Program.cs	Updates hosting pattern and renames method from BuildWebHost to CreateHostBuilder
src/Swashbuckle.AspNetCore.Cli/Program.cs	Updates hosting pattern in CLI service provider creation

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 94.28%. Comparing base (1e7fa33) to head (a1bcdaa).
⚠️ Report is 1 commits behind head on master.
✅ All tests successful. No failed tests found.

Additional details and impacted files

@@           Coverage Diff           @@
##           master    #3517   +/-   ##
=======================================
  Coverage   94.28%   94.28%           
=======================================
  Files         110      110           
  Lines        3816     3816           
  Branches      722      722           
=======================================
  Hits         3598     3598           
  Misses        218      218           

Flag	Coverage Δ
Linux	94.28% <ø> (ø)
Windows	94.28% <ø> (ø)
macOS	94.28% <ø> (ø)

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