Add CMakeUserPresets.json to .gitignore (facebookincubator#9470)

Summary:
Ensure user-specific CMake presets do not show up in git.

CMake >= 3.19 allows the use of presets to specify project settings. CMakeUserPresets.json is used to store user-specific settings which should not be checked in to git.

Pull Request resolved: facebookincubator#9470

Reviewed By: kgpai

Differential Revision: D56169262

Pulled By: pedroerp

fbshipit-source-id: a9cdd2ff528c447f3d61cd5d61360dde7971ff8a

.gitignore

@@ -279,6 +279,7 @@ settings.json
 
 # User's build configuration
 Makefile.config
+CMakeUserPresets.json
 
 # build, distribute, and bins (+ python proto bindings)
 build