Add MusculoskeletalAnalysis extension (#2130)

* Add files via upload

* Update MusculoskeletalAnalysis.s4ext

* Update MusculoskeletalAnalysis.s4ext

* Updated Category to Quantification

* STYLE: Convert MusculoskeletalAnalysis.s4ext to LF line ending

* Fix MusculoskeletalAnalysis metadata

Improve description and fix screenshoturls specifying GitHub raw URL

* ENH: Convert MusculoskeletalAnalysis s4ext to json file

---------

Co-authored-by: jszatkowskiwustl <[email protected]>
Co-authored-by: Jean-Christophe Fillion-Robin <[email protected]>

MusculoskeletalAnalysis.json

@@ -0,0 +1,8 @@
+{
+  "$schema": "https://raw.githubusercontent.com/Slicer/Slicer/main/Schemas/slicer-extension-catalog-entry-schema-v1.0.0.json#",
+  "build_dependencies": [],
+  "build_subdirectory": ".",
+  "category": "Quantification",
+  "scm_revision": "main",
+  "scm_url": "https://github.com/WashUMusculoskeletalCore/Slicer-MusculoskeletalAnalysis.git"
+}