feat: use hex validator addresses in precompiles

[luchenqun]

Summary

• use EVM hex validator addresses for staking and distribution precompile inputs
• convert hex validator addresses to SDK bech32 internally
• update Solidity helpers, ABI artifacts, and related tests

Reference: evmos/evmos#2122

Testing

• go test ./precompiles/distribution ./precompiles/staking ./precompiles/testutil/contracts -tags=test -count=1
• go test ./tests/integration/precompiles/distribution ./tests/integration/precompiles/staking -tags=test -run TestDoesNotExist -count=1
• cd contracts && npx hardhat compile --force

[greptile-apps]

PR author is not in the allowed authors list.

[aljo242]

ci has not run on this pr: all workflows (tests, lint, solhint, slither, solidity-test, json-rpc compatibility) are in action_required state -- fork pr, needs maintainer approval to trigger. the only green check is the mergify gate summary, not actual test results.

branch is also 4 commits behind main (missing #1176 and #1187, both statedb fixes). needs a rebase before ci can be meaningfully evaluated.

given the breaking api surface (all staking and distribution precompile callers need new abis and redeployment), this needs ci green + rebase before review.