[llvm] [MCA] Enable customization of individual instructions (PR #155420)

[Roman Belenov via llvm-commits]

================
@@ -42,19 +43,91 @@ CustomBehaviour::getEndViews(llvm::MCInstPrinter &IP,
   return std::vector<std::unique_ptr<View>>();
 }
 
+class CustomInstrument : public Instrument {
----------------
r-belenov wrote:

PS Pushed the changes that remove targetIM

https://github.com/llvm/llvm-project/pull/155420