[MonacoPreviewHandler][Settings] Resolve preview handler race (#16180)

* Register .markdown with the correct handler

* Fix spelling

* Move file name extensions from "expect.txt" to "excludes.txt"

* Revert "Move file name extensions from "expect.txt" to "excludes.txt""

This reverts commit 710d5a4968.
I must have misunderstood the instructions.

* Revert "Register .markdown with the correct handler"

This reverts commit 5c37b009f3.

* Work in progress

* Code ready for testing

* Update excludes.txt

* Update excludes.txt

* Update modulesRegistry.h

* Update modulesRegistry.h

For the want of an exclamation mark, a kingdom is lost!

* Update modulesRegistry.h

* Work on modulesRegistry.h per code review in 16180

Removed all previous exclusions from Monaco preview handler. Added a new exclusion: SVGZ. It's a binary file that Monaco cannot, in any meaningful way, read.

* Update expect.txt

* Update accessory files

* Disable machine-wide checks for performance reasons

src/settings-ui/Settings.UI/Strings/en-us/Resources.resw

@@ -617,7 +617,7 @@
     <value>Show recently used strings</value>
   </data>
   <data name="FileExplorerPreview_ToggleSwitch_Preview_MD.Header" xml:space="preserve">
-    <value>Enable Markdown (.md) preview</value>
+    <value>Enable Markdown preview  (.md, .markdown, .mdown, .mkdn, .mkd, .mdwn, .mdtxt, .mdtext)</value>
     <comment>Do not loc "Markdown".  Do you want this feature on / off</comment>
   </data>
   <data name="FileExplorerPreview_ToggleSwitch_Preview_Monaco.Header" xml:space="preserve">