pgsql: Improve scripting language in pgbench

Improve scripting language in pgbench

Added:
- variable now might contain integer, double, boolean and null values
- functions ln, exp
- logical AND/OR/NOT
- bitwise AND/OR/NOT/XOR
- bit right/left shift
- comparison operators
- IS [NOT] (NULL|TRUE|FALSE)
- conditional choice (in form of when/case/then)

New operations and functions allow to implement more complicated test scenario.

Author: Fabien Coelho with minor editorization by me
Reviewed-By: Pavel Stehule, Jeevan Ladhe, me
Discussion: https://www.postgresql.org/message-id/flat/alpine(dot)DEB(dot)2(dot)10(dot)1604030742390(dot)31618(at)sto

Branch
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master

Details
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https://git.postgresql.org/pg/commitdiff/bc7fa0c15c590ddf4872e426abd76c2634f22aca

Modified Files
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doc/src/sgml/ref/pgbench.sgml | 223 +++++++++++-
src/bin/pgbench/exprparse.y | 195 ++++++++++-
src/bin/pgbench/exprscan.l | 55 ++-
src/bin/pgbench/pgbench.c | 484 +++++++++++++++++++++++----
src/bin/pgbench/pgbench.h | 24 +-
src/bin/pgbench/t/001_pgbench_with_server.pl | 171 ++++++++--
6 files changed, 1026 insertions(+), 126 deletions(-)