Add boost helpers

[tsudmi]

No description provided.

[github-actions]

Forge code coverage:

File	% Lines	% Statements	% Branches	% Funcs
src/BoostHelpers.sol	92.73% (51/55)	94.20% (65/69)	58.33% (7/12)	100.00% (5/5)
src/MerkleDistributor.sol	98.75% (79/80)	95.74% (90/94)	80.00% (12/15)	100.00% (11/11)
src/OsTokenVaultEscrowAuth.sol	100.00% (6/6)	100.00% (9/9)	100.00% (0/0)	100.00% (2/2)
src/StakeHelpers.sol	70.27% (52/74)	71.72% (71/99)	36.36% (4/11)	85.71% (6/7)
src/StrategiesRegistry.sol	100.00% (24/24)	100.00% (26/26)	100.00% (8/8)	100.00% (5/5)
src/StrategyProxy.sol	76.92% (10/13)	63.64% (7/11)	50.00% (1/2)	100.00% (5/5)
src/VaultUserLtvTracker.sol	92.86% (26/28)	93.75% (30/32)	66.67% (4/6)	100.00% (4/4)
src/leverage/AaveLeverageStrategy.sol	97.14% (34/35)	96.77% (30/31)	75.00% (3/4)	100.00% (8/8)
src/leverage/EthAaveLeverageStrategy.sol	100.00% (14/14)	100.00% (14/14)	100.00% (0/0)	100.00% (4/4)
src/leverage/GnoAaveLeverageStrategy.sol	0.00% (0/14)	0.00% (0/14)	0.00% (0/1)	0.00% (0/4)
src/leverage/LeverageStrategy.sol	93.95% (233/248)	94.52% (293/310)	75.51% (37/49)	100.00% (24/24)
Total	89.51% (529/591)	89.56% (635/709)	70.37% (76/108)	93.67% (74/79)