Add hit/miss metrics for compiled code caches

[martint]

I suspect that the caches for compiled code are not very effective for large, varied workloads. We should add cache hit/miss metrics and expose them via JMX to be able to test this hypothesis.

Classes that need to be instrumented: ExpressionCompiler, JoinCompiler, JoinFilterFunctionCompiler, JoinProbeCompiler, OrderingCompiler

[raghavsethi]

Merged this.

[martint]

Only ExpressionCompiler is implemented.

[nezihyigitbasi]

Is anyone working on this issue? Otherwise I will go for it.

[nezihyigitbasi]

@ebyhr Will you also handle JoinCompiler and JoinProbeCompiler classes, which require some refactoring? I was planning to work on those when I assigned this issue to myself (after I got no response to my ping), so I will be happy to take those if you don't have any plans, otherwise feel free to assign the issue to yourself.

[ebyhr]

Sorry @nezihyigitbasi, I overlooked your ping.
I don't have any plans, so I would be grateful if you deal this :)

[nezihyigitbasi]

Now that #7333 is merged, closing this one.