Redesign WebView2 TOC & clarify article titles

[mikehoffms]

Rendered TOC for review:
https://review.learn.microsoft.com/microsoft-edge/webview2/?branch=pr-en-us-3124
Before:
https://learn.microsoft.com/microsoft-edge/webview2/

Confirmed that each article in live TOC exists in PR's rendered TOC.

Objectives of this TOC redesign:

• Removes abstract TOC buckets ("Fundamentals", "Advanced") and directly/immediately shows their content.
  • Avoid unnecessary levels of deep nesting, per IA & style guide (platform manual).
  • Uses more topical, specific TOC buckets, promoting the tech key words users are looking for, and a generally flatter design that reveals more articles and specific topics by default.
  • Enables more flexible grouping/placement of the articles.
  • Eliminates top-level buckets that are low-value & abstract; promotes the high-value, keyword-based nodes that were contained in them.
  • Eliminates a UX of guessing and having to explore into the abstract TOC nodes.
  • Makes maintenance/improvement easier.
• Groups together articles such as distribution.md & versioning.md that were spread apart between two different TOC buckets (Fundamentals & Deployment).
• Instead of mixing two different schemes for the TOC (group by tech topic vs. group by Fundamentals/Advanced), the new design uses only a single scheme: group by tech topic.
  • Within any topical TOC bucket, per industry convention, articles about basics/fundamentals are first, and advanced/specialized articles are below them.
    • Paragraph 1 in an article is an available place to tell user how to decide if article is relevant/required for them.

This PR also makes the following changes:

• Changes article title from:
  "Understand the different WebView2 SDK versions"
  to:
  "Prerelease and Release SDKs for WebView2"
  to be more specific (than "versions") and provide the key words.
  https://review.learn.microsoft.com/en-us/microsoft-edge/webview2/concepts/versioning?branch=pr-en-us-3124
• Changes article title from "Interop of native-side and web-side code" to "Interop of native and web code".
  https://review.learn.microsoft.com/en-us/microsoft-edge/webview2/how-to/communicate-btwn-web-native?branch=pr-en-us-3124

Mapping from existing TOC (left) to redesigned TOC (right):

This PR 3124 replaces forked July 2023 PR #2725, which lists the irrelevant file archive.md as entirely changed by that PR, yet not at all changed by that PR.

AB#50063950

[learn-build-service-prod]

Learn Build status updates of commit 6e53a53:

✅ Validation status: passed

File	Status	Preview URL	Details
microsoft-edge/developer/index.yml	✅Succeeded	View
microsoft-edge/index.yml	✅Succeeded	View
microsoft-edge/toc.yml	✅Succeeded	View
microsoft-edge/webview2/code-samples-links.md	✅Succeeded	View
microsoft-edge/webview2/concepts/frames.md	✅Succeeded	View
microsoft-edge/webview2/concepts/navigation-events.md	✅Succeeded	View
microsoft-edge/webview2/concepts/overview-features-apis.md	✅Succeeded	View
microsoft-edge/webview2/concepts/process-related-events.md	✅Succeeded	View
microsoft-edge/webview2/concepts/versioning.md	✅Succeeded	View
microsoft-edge/webview2/concepts/working-with-local-content.md	✅Succeeded	View
microsoft-edge/webview2/get-started/get-started.md	✅Succeeded	View
microsoft-edge/webview2/get-started/win32.md	✅Succeeded	View
microsoft-edge/webview2/get-started/winui.md	✅Succeeded	View
microsoft-edge/webview2/get-started/winui2.md	✅Succeeded	View
microsoft-edge/webview2/get-started/wpf.md	✅Succeeded	View
microsoft-edge/webview2/how-to/communicate-btwn-web-native.md	✅Succeeded	View
microsoft-edge/webview2/how-to/customize-ui.md	✅Succeeded	View
microsoft-edge/webview2/how-to/set-preview-channel.md	✅Succeeded	View
microsoft-edge/webview2/samples/deployment-samples.md	✅Succeeded	View
microsoft-edge/webview2/samples/webview2apissample.md	✅Succeeded	View

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