Add how-to: Test prerelease .NET SDKs locally with global.json paths (#52893)

* Add how-to article: Test prerelease .NET SDKs locally with global.json paths

This adds a step-by-step how-to guide for using the sdk.paths property
in global.json (new in .NET 10) to install and test prerelease SDKs in
a project-local directory without modifying system-wide installations.

The article covers:
- Installing a prerelease SDK with dotnet-install scripts
- Configuring global.json with the paths property
- Installing workloads (MAUI, wasm-tools) on the local SDK
- Team convenience scripts for cross-platform onboarding
- CI integration with GitHub Actions
- Cleanup and limitations

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

* Clarify what 'host' means on first mention in prerequisites

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

* Simplify article: clarify host, remove pre-.NET 10 guidance, deduplicate cleanup

- Explain 'host' as the system-wide dotnet installation on first mention
- Remove all ./.dotnet/dotnet fallback instructions after prerequisites
- Simplify workload section to use plain dotnet commands
- Replace duplicate 'Undo all changes' section with link to Clean up
- Add brief mention that paths supports multiple entries
- Remove redundant IMPORTANT callout from quick start section
- Convert quick start intro from TIP callout to plain text

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

* Workload section: clarify running from global.json folder, verify with dotnet --info

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

* Workload commands: document DOTNET_ROOT gap, use local binary

Workload commands (install, list) store metadata relative to the dotnet
root of the host process. When using the system host with sdk.paths,
workloads end up in the system installation rather than the local one.
This is a known gap (dotnet/sdk#49825).

Updated all workload examples to use ./.dotnet/dotnet directly, with
an IMPORTANT callout explaining why and linking to the tracking issue.

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

* Address PR review feedback

- Add ai-usage: ai-assisted to front matter
- Fix missing space and clarify PATH behavior (session-only, not permanent)
- Reword prerequisite to avoid mixing SDK/host terminology
- Fix inconsistent tab title: 'Windows PowerShell' -> 'Windows (PowerShell)'

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

* Address review feedback from gewarren

- Apply wording suggestions (parentheses style, 'how-to article', remove 'Note that')
- Add backticks to PATH in Limitations section
- Use 'might' instead of 'may' per style guide
- Convert team install scripts to tabbed layout (macOS/Linux + Windows tabs)

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

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Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

Author: jfversluis