perf(contracts): internal compress

[philsippl]

Makes the function compress internal, which leads to the compiler inlining the function in the caller contract instead of DELEGATECALL'ing it.

Of course only updates (and single insertions) benefit from this, not the (storage dominated) batch insertion hotpath.

Hash Function	Before (public)	After (internal)	Change
Poseidon2T2	7,357 gas	6,360 gas	-13.5%

Updates (1000-leaf tree, depth 30)

	public	internal	savings
fs update leaf 0	427,473	395,557	-31,916 (-7.5%)
fs update leaf 500	427,574	395,658	-31,916 (-7.5%)
fs update leaf 999	423,458	391,542	-31,916 (-7.5%)

insertMany (per-leaf average)

public	internal	savings
fs insertMany(10)	138,170	134,393
fs insertMany(100)	60,518	59,303
fs insertMany(1000)	53,261	52,274