[DevDocs] More content and restructure (#40165)

## Summary of the Pull Request
Accumulated information from internal transition about the modules
development, and reworked it to be added in dev docs. Also the dev docs
intself was restructured to be more organized. New pages was
verified by transition team.

## PR Checklist
- [x] **Dev docs:** Added/updated

---------

Co-authored-by: Zhaopeng Wang (from Dev Box) <zhaopengwang@microsoft.com>
Co-authored-by: Hao Liu <liuhao3418@gmail.com>
Co-authored-by: Peiyao Zhao <105847726+zhaopy536@users.noreply.github.com>
Co-authored-by: Mengyuan <162882040+chenmy77@users.noreply.github.com>
Co-authored-by: zhaopeng wang <33367956+wang563681252@users.noreply.github.com>
Co-authored-by: Jaylyn Barbee <51131738+Jaylyn-Barbee@users.noreply.github.com>

doc/devdocs/tools/readme.md

@@ -11,9 +11,6 @@ Following tools are currently available:
 * [BugReportTool](bug-report-tool.md) - A tool to collect logs and system information for bug reports.
 * [Build tools](build-tools.md) - A set of scripts that help building PowerToys.
 * [Clean up tool](clean-up-tool.md) - A tool to clean up the PowerToys installation.
-* [FancyZones hit test](fancyzones-hit-test.md) - A tool to test FancyZones layout selection logic.
-* [FancyZones draw layout test](fancyzones-draw-layout-test.md) - A tool to test FancyZones layout drawing logic.
-* [FancyZones zonable tester](fancyzones-zonable-tester.md) - A tool to test if a window is zonable.
 * [Monitor info report](monitor-info-report.md) - A small diagnostic tool which helps identifying WinAPI bugs related to the physical monitor detection.
 * [project template](/tools/project_template/README.md) - A Visual Studio project template for a new PowerToys project.
 * [StylesReportTool](styles-report-tool.md) - A tool to collect information about an open window.