C++: "IR" means "Aliased SSA IR"

This change makes the public IR.qll module resolve to the flavor of the IR that we want queries to use. Today, this is the aliased SSA flavor of the IR. Should we add additional IR iterations in the future, we'll update IR.qll to resolve to whichever one we consider the default.

I moved the PrintIR.ql and IRSanity.ql queries into the internal directories of the corresponding flavors. There's still a PrintIR.ql and an IRSanity.ql in the public IR directory, which use the same IR flavor as the public IR.qll.

Author: dave-bartolomeo

cpp/ql/src/semmle/code/cpp/ir/AliasedSSAIR.qll

@@ -1 +1,3 @@
-import internal.raw_ir.IR
+// Most queries should operate on the aliased SSA IR, so that's what we expose
+// publically as the "IR".
+import internal.aliased_ssa_ir.IR

cpp/ql/src/semmle/code/cpp/ir/IR.qll

@@ -5,4 +5,4 @@
  * @id cpp/ir-sanity-check
  */
 
-import internal.raw_ir.IRSanity
+import internal.aliased_ssa_ir.IRSanity

cpp/ql/src/semmle/code/cpp/ir/IRSanity.ql

@@ -5,4 +5,4 @@
  * @kind graph
  */
 
-import PrintIR
+import internal.aliased_ssa_ir.PrintIR

cpp/ql/src/semmle/code/cpp/ir/PrintAliasedSSAIR.qll

@@ -5,4 +5,4 @@
  * @id cpp/aliased-ssa-ir-sanity-check
  */
 
-import internal.aliased_ssa_ir.IRSanity
+import IRSanity

cpp/ql/src/semmle/code/cpp/ir/PrintIR.ql

@@ -5,4 +5,4 @@
  * @kind graph
  */
 
-import PrintAliasedSSAIR
+import PrintIR