prettier comments

feat(ctb): preserve legacy ETH invariant

ctb: Add echidna tests for Hashing

Preserves the invariant in LegacyERC20ETH that balanceOf(x) is always
the same as address(x).balance. balanceOf is the only function that was
not being blocked and contracts may exist that rely on this behavior.

fix(cmn): BaseServiceV2 options parsing bug

feat(cmn): make logLevel a default option

ctb: Add echidna tests for metering

maint(ctb): move default sender to constants

op-node: Preallocate slice

Updates BaseServiceV2 so that logLevel is a default option to any new
instantiation of BaseServiceV2. Avoids people having to include hacky
code to set the log level.

build(deps): bump express from 4.17.1 to 4.17.3

Moves the DEFAULT_L2_SENDER variable to Constants.sol since it's being
shared by both CrossDomainMessenger and OptimismPortal.

feat(ctb): add gas estimation logic to portal

Adds the same special gas estimation logic that we just added to the
CrossDomainMessenger into the OptimismPortal.

Fixes a bug in BaseServiceV2 where options would not be parsed correctly
when passed directly into the constructor rather than via the
environment or command line arguments.

fix: migration gaslimit

feat(ctb): update portal gas amount