Get rid of dotnet test runner

[nightskylark]

Summary

This PR removes the .NET dependency from the DevExtreme QUnit browser runner by replacing the legacy ASP.NET Core runner with a Node.js implementation, while preserving the existing runner behavior and endpoint contract.

Motivation

The previous runner required a .NET toolchain only for QUnit execution. This increased CI/setup complexity and made long-term maintenance harder.
The new implementation keeps the same workflow but runs fully on Node.js.

What was changed

1. Replaced legacy .NET QUnit runner with Node.js

• Implemented a Node-based runner at packages/devextreme/testing/runner/index.js.
• Kept legacy-compatible routes and semantics for:
  • suite/category discovery,
  • run pages (/run, /main/runall, /main/runsuite),
  • test lifecycle notifications,
  • results saving/reporting (Results.xml, misc/raw logs),
  • vector map helper endpoints,
  • static file serving.

2. Removed .NET artifacts and configuration

• Deleted legacy C# runner sources and project files:
  • packages/devextreme/testing/runner/**/*.cs
  • packages/devextreme/testing/runner/runner.csproj
  • old MVC views and model/controller/tool files.
• Removed obsolete solution:
  • packages/devextreme/build/build-dotnet.sln
• Removed obsolete VSCode runner configs:
  • packages/devextreme/testing/runner/.vscode/*

3. Updated scripts and CI to be Node-only

• packages/devextreme/testing/launch: now starts node testing/runner/index.js.
• packages/devextreme/docker-ci.sh: runner startup switched from runner.dll to Node runner.
• packages/devextreme/package.json: removed dotnet build from dev script.
• .github/actions/run-qunit-tests/action.yml: removed .NET build step.
• .github/workflows/qunit_tests.yml and packages/devextreme/project.json: removed DOTNET_* env usage.

4. Security and robustness improvements

• Moved large inline HTML pages to dedicated templates:
  • packages/devextreme/testing/runner/templates/*.template.html
• Added safe template rendering and escaping in Node runner.
• Replaced dynamic string URL concatenation in getJSON with query params object for suite loading.
• Improved cache-buster handling (DX_HTTP_CACHE) by URL-encoding values.

5. CI fixes after migration

• Added HEAD handling for run endpoints used by readiness checks.
• Fixed SystemJS mapping for @preact/signals-core.
• Added fallback when theme bundles directory is missing.
• Fixed vector map output parsing for non-JSON mode (trailing ; / assignment parsing).

6. Maintainability refactor

• Split the monolithic runner into focused modules under packages/devextreme/testing/runner/lib/:
  • http, logger, pages, results, static, suites, templates, utils, vectormap.
• Reduced index.js from ~1550 lines to an orchestration layer (~446 lines).

Compatibility notes

• No intentional functional changes in test execution behavior.
• Existing runner endpoints and overall flow are preserved.

[Copilot]

Pull request overview

This PR removes the .NET (ASP.NET Core) dependency from the DevExtreme QUnit browser runner and replaces it with a functionally equivalent Node.js implementation. The legacy runner required a .NET 8 toolchain solely for QUnit test execution, making CI/setup unnecessarily complex.

Changes:

• Replaces the ASP.NET Core runner (C# controllers, models, Razor views, runner.csproj, build-dotnet.sln) with a new Node.js runner (index.js + modular lib/ files), preserving all existing HTTP routes and behavior.
• Migrates inline Razor HTML to standalone .template.html files with a custom {{{raw}}}/{{escaped}} template engine and adds safe HTML escaping.
• Updates CI workflows, scripts, and package.json to remove all .NET build steps.

Reviewed changes

Copilot reviewed 44 out of 44 changed files in this pull request and generated 3 comments.

Show a summary per file

File	Description
packages/devextreme/testing/runner/index.js	New Node.js server replacing the entire .NET runner
packages/devextreme/testing/runner/lib/vectormap.js	Vector map service (spawning helper server, console app)
packages/devextreme/testing/runner/lib/utils.js	Shared utilities (parsing, escaping, file I/O)
packages/devextreme/testing/runner/lib/templates.js	Template renderer with escaping support
packages/devextreme/testing/runner/lib/suites.js	Test suite/category discovery
packages/devextreme/testing/runner/lib/static.js	Static file serving with directory listings
packages/devextreme/testing/runner/lib/results.js	XML results generation and text reporting
packages/devextreme/testing/runner/lib/pages.js	Page renderers (index, run-all, run-suite)
packages/devextreme/testing/runner/lib/logger.js	Colored console + file logger
packages/devextreme/testing/runner/lib/http.js	HTTP response helpers
packages/devextreme/testing/runner/templates/*.template.html	HTML templates for runner UI pages
.github/actions/run-qunit-tests/action.yml	Removed dotnet build CI step
.github/workflows/qunit_tests.yml	Removed DOTNET env variables
packages/devextreme/package.json	Removed dotnet build from dev script
packages/devextreme/project.json	Removed DOTNET_* env pass-throughs
packages/devextreme/docker-ci.sh	Updated runner startup command
packages/devextreme/testing/launch	Updated to launch Node.js runner
All deleted C# files	Legacy .NET runner source removed