Use compiled expression in AliasToBeanResultTransformer

[bahusoid]

Possible breaking change: As now expression is compiled on first transformation - this transformer can't be reused for different queries. Transfomer can still be reused but only for the same query.

Perf comparison for 5 aliases and 50 000 transformations on my machine (see #2015 with side by side comparison): 300 ms vs 15 ms for Compiled version

[hazzik]

We can cache the compiled delegate by aliases to avoid breaking changes.

[bahusoid]

Yeah. But is it worth it? Current transformer design means that lookup is required on each record transformation. I don't think that this reusing is commonly used (as our docs say nothing about it) and from my tests didn't saves much. If you are in to such optimizations - you better cache transformer per query for yourself.