AliasAnalysis: make AliasAnalysis a function analysis and simplify the cache keys

Instead of caching alias results globally for the module, make AliasAnalysis a FunctionAnalysisBase which caches the alias results per function.
Why?
* So far the result caches could only grow. They were reset when they reached a certain size. This was not ideal. Now, they are invalidated whenever the function changes.
* It was not possible to actually invalidate an alias analysis result. This is required, for example in TempRValueOpt and TempLValueOpt (so far it was done manually with invalidateInstruction).
* Type based alias analysis results were also cached for the whole module, while it is actually dependent on the function, because it depends on the function's resilience expansion. This was a potential bug.

I also added a new PassManager API to directly get a function-base analysis:
    getAnalysis(SILFunction *f)

The second change of this commit is the removal of the instruction-index indirection for the cache keys. Now the cache keys directly work on instruction pointers instead of instruction indices. This reduces the number of hash table lookups for a cache lookup from 3 to 1.
This indirection was needed to avoid dangling instruction pointers in the cache keys. But this is not needed anymore, because of the new delayed instruction deletion mechanism.

lib/SILOptimizer/Transforms/ARCCodeMotion.cpp

@@ -1189,7 +1189,7 @@ public:
       POA->invalidateFunction(F);
 
     auto *PO = POA->get(F);
-    auto *AA = PM->getAnalysis<AliasAnalysis>();
+    auto *AA = PM->getAnalysis<AliasAnalysis>(F);
     auto *RCFI = PM->getAnalysis<RCIdentityAnalysis>()->get(F);
 
     llvm::SpecificBumpPtrAllocator<BlockState> BPA;