[clang-tools-extra] [clang-tidy] introduce a must use check (PR #76101)

[Piotr Zegar via cfe-commits]

================
@@ -0,0 +1,28 @@
+.. title:: clang-tidy - misc-must-use
+
+misc-must-use
+=============
+
+Allow strictly enforcing that variables are used for specific classes,
+even with they would not be normally warned using `-Wunused-variable` due 
----------------
PiotrZSL wrote:

consider changing check in a way, so it would not overlap with -Wunused-variable

https://github.com/llvm/llvm-project/pull/76101