fix: handle unmodified validators

[twoeths]

Motivation

Some validators.get(i) may call and it's tracked in viewsChanged, right now we compute its root in batch while we should not

Description

• commit all validators first
• filter out those have roots already
• update benchmark to test it

Benchmark
with half of validators.get() called without modifying anything

• current

BeaconState ViewDU partially modified tree vc=200000 numModified=100000
    ✓ BeaconState ViewDU batchHashTreeRoot vc=200000                      3.311916 ops/s    301.9400 ms/op        -         40 runs   20.7 s
    ✓ BeaconState ViewDU batchHashTreeRoot - commit step vc=200000        3.735825 ops/s    267.6785 ms/op        -         50 runs   20.5 s
    ✓ BeaconState ViewDU batchHashTreeRoot - hash step vc=200000          21.26964 ops/s    47.01538 ms/op        -         44 runs   25.0 s
    ✓ BeaconState ViewDU hashTreeRoot() vc=200000                         2.024038 ops/s    494.0618 ms/op        -         34 runs   22.1 s
    ✓ BeaconState ViewDU hashTreeRoot - commit step vc=200000             15.08328 ops/s    66.29857 ms/op        -        101 runs   21.8 s
    ✓ BeaconState ViewDU hashTreeRoot - validator tree creation vc=100    6.294561 ops/s    158.8673 ms/op        -         57 runs   20.4 s

• this PR

 BeaconState ViewDU partially modified tree vc=200000 numModified=100000
    ✓ BeaconState ViewDU batchHashTreeRoot vc=200000                      5.816562 ops/s    171.9229 ms/op        -         57 runs   20.5 s
    ✓ BeaconState ViewDU batchHashTreeRoot - commit step vc=200000        6.362287 ops/s    157.1762 ms/op        -         67 runs   20.3 s
    ✓ BeaconState ViewDU batchHashTreeRoot - hash step vc=200000          36.34095 ops/s    27.51717 ms/op        -         52 runs   20.7 s
    ✓ BeaconState ViewDU hashTreeRoot() vc=200000                         2.066677 ops/s    483.8685 ms/op        -         33 runs   20.7 s
    ✓ BeaconState ViewDU hashTreeRoot - commit step vc=200000             16.28455 ops/s    61.40789 ms/op        -        100 runs   20.2 s
    ✓ BeaconState ViewDU hashTreeRoot - validator tree creation vc=100    6.153062 ops/s    162.5207 ms/op        -         57 runs   20.3 s