Add JIT deform_counter

Add JIT deform_counter

generation_counter includes time spent on both JIT:ing expressions
and tuple deforming which are configured independently via options
jit_expressions and jit_tuple_deforming.  As they are  combined in
the same counter it's not apparent what fraction of time the tuple
deforming takes.

This adds deform_counter dedicated to tuple deforming, which allows
seeing more directly the influence jit_tuple_deforming is having on
the query. The counter is exposed in EXPLAIN and pg_stat_statements
bumpin pg_stat_statements to 1.11.

Author: Dmitry Dolgov <[email protected]>
Reviewed-by: Pavel Stehule <[email protected]>
Reviewed-by: Daniel Gustafsson <[email protected]>
Discussion: https://postgr.es/m/20220612091253[email protected]