fix: use State for consistency, add natspec on SwapResults

[snreynolds]

Some comments from #848 and I want to move the Positions struct to be consistent with Pool.State

[github-actions]

Forge code coverage:

File	% Lines	% Statements	% Branches	% Funcs
src/ERC6909.sol	82.61% (19/23)	78.57% (22/28)	100.00% (2/2)	85.71% (6/7)
src/ERC6909Claims.sol	100.00% (6/6)	100.00% (8/8)	100.00% (2/2)	100.00% (1/1)
src/Extsload.sol	0.00% (0/28)	0.00% (0/30)	0.00% (0/2)	100.00% (3/3)
src/Exttload.sol	0.00% (0/15)	0.00% (0/16)	0.00% (0/1)	50.00% (1/2)
src/NoDelegateCall.sol	66.67% (2/3)	75.00% (3/4)	100.00% (1/1)	100.00% (3/3)
src/PoolManager.sol	98.97% (96/97)	97.74% (130/133)	89.47% (17/19)	100.00% (20/20)
src/ProtocolFees.sol	83.33% (20/24)	83.87% (26/31)	80.00% (4/5)	100.00% (6/6)
src/libraries/BitMath.sol	18.18% (2/11)	18.18% (2/11)	0.00% (0/4)	100.00% (2/2)
src/libraries/CurrencyDelta.sol	33.33% (3/9)	45.45% (5/11)	100.00% (0/0)	100.00% (3/3)
src/libraries/CurrencyReserves.sol	14.29% (1/7)	14.29% (1/7)	0.00% (0/1)	100.00% (5/5)
src/libraries/CustomRevert.sol	0.00% (0/35)	0.00% (0/35)	100.00% (0/0)	100.00% (8/8)
src/libraries/FullMath.sol	68.97% (20/29)	72.73% (24/33)	33.33% (2/6)	100.00% (2/2)
src/libraries/Hooks.sol	94.12% (80/85)	95.00% (133/140)	92.00% (23/25)	100.00% (14/14)
src/libraries/LPFeeLibrary.sol	90.00% (9/10)	93.75% (15/16)	100.00% (1/1)	100.00% (7/7)
src/libraries/LiquidityMath.sol	0.00% (0/4)	0.00% (0/4)	0.00% (0/1)	100.00% (1/1)
src/libraries/Lock.sol	0.00% (0/3)	0.00% (0/3)	100.00% (0/0)	100.00% (3/3)
src/libraries/NonzeroDeltaCount.sol	0.00% (0/7)	0.00% (0/7)	100.00% (0/0)	100.00% (3/3)
src/libraries/ParseBytes.sol	0.00% (0/3)	0.00% (0/3)	100.00% (0/0)	100.00% (3/3)
src/libraries/Pool.sol	94.23% (147/156)	93.60% (161/172)	98.08% (51/52)	100.00% (13/13)
src/libraries/Position.sol	52.63% (10/19)	57.14% (12/21)	100.00% (3/3)	100.00% (3/3)
src/libraries/ProtocolFeeLibrary.sol	20.00% (2/10)	20.00% (2/10)	100.00% (0/0)	100.00% (4/4)
src/libraries/SafeCast.sol	100.00% (12/12)	100.00% (19/19)	100.00% (6/6)	100.00% (6/6)
src/libraries/SqrtPriceMath.sol	60.42% (29/48)	69.84% (44/63)	58.33% (7/12)	100.00% (9/9)
src/libraries/StateLibrary.sol	71.43% (45/63)	79.31% (69/87)	100.00% (4/4)	100.00% (14/14)
src/libraries/SwapMath.sol	80.77% (21/26)	81.48% (22/27)	100.00% (6/6)	100.00% (2/2)
src/libraries/TickBitmap.sol	40.00% (12/30)	50.00% (18/36)	66.67% (2/3)	100.00% (4/4)
src/libraries/TickMath.sol	37.11% (36/97)	56.94% (82/144)	95.83% (23/24)	100.00% (4/4)
src/libraries/TransientStateLibrary.sol	70.00% (7/10)	76.92% (10/13)	100.00% (0/0)	100.00% (5/5)
src/libraries/UnsafeMath.sol	0.00% (0/2)	0.00% (0/2)	100.00% (0/0)	100.00% (2/2)
src/types/BalanceDelta.sol	0.00% (0/2)	0.00% (0/2)	100.00% (0/0)	100.00% (2/2)
src/types/BeforeSwapDelta.sol	0.00% (0/2)	0.00% (0/2)	100.00% (0/0)	100.00% (2/2)
src/types/Currency.sol	59.09% (13/22)	70.00% (21/30)	75.00% (6/8)	100.00% (6/6)
src/types/PoolId.sol	0.00% (0/1)	0.00% (0/1)	100.00% (0/0)	100.00% (1/1)
src/types/Slot0.sol	0.00% (0/8)	0.00% (0/8)	100.00% (0/0)	100.00% (8/8)
Total	68.53% (1350/1970)	71.28% (1812/2542)	41.98% (272/648)	83.05% (397/478)