Add benchmarking to DDB v2 mapper

[RanVaknin]

POC numbers for GetItem:

Payload Size	v1 Mapper	v2 Enhanced Client	v2 Mapper (POC)	v2 Mapper vs v1	v2 Mapper vs Enhanced
TINY (1 field)	4.11M ops/s	3.23M ops/s	2.64M ops/s	-36%	-18%
SMALL (3 fields + binary)	2.30M ops/s	1.50M ops/s	1.74M ops/s	-24%	+16% faster
HUGE (nested maps)	250K ops/s	129K ops/s	214K ops/s	-14%	+66% faster
HUGE_FLAT (63 string fields)	298K ops/s	290K ops/s	300K ops/s	+0.6%	+3% faster

[sonarqubecloud]

Quality Gate failed

Failed conditions
2 Security Hotspots
18.3% Coverage on New Code (required ≥ 80%)
4.0% Duplication on New Code (required ≤ 3%)
D Reliability Rating on New Code (required ≥ A)

See analysis details on SonarQube Cloud

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