docker: update node version to 16

Version Packages

Develop -> Master PR

feat: add batch-tx submitter custom encoding and test vectors

fix: minor improvements to empty sequencer block handling

Prior to this commit, an empty block would be submitted to the taskCh
before sanity check whether or not it was empty. This assertion is moved
up to fail before submitting the task.

It seems the placement of the check before was done to get around the
StreamUncle unit test, which would allow commit to submit an empty task
before ultimately failing. Now that the test is modified to reflect the
expected behavior of the sequencer, this placement is no longer
necessary.

This commit fixes a bug in the way txCount was used for detecting and
aborting empty blocks. Previously, txCount was incremented immediately
after popping off the new transaction but before it is executed. This
was incorrect, as the transaction can still be rejected for nonce/gas
errors later on. Instead, we modify the logic only count transactions
that are successfully added, and utilize the existing w.current.tcount
member to implement the detection.

With empty block mining logic totally removed in the prior commit,
worker.commit is now only called with update=true. We can now safely
remove the argument and the affected codepaths.

As of the prior commit, all calls to the `commit` pass a noempty value
of true, indicating that the sequencer should not start mining empty
blocks. Therefore, we can remove all usage of noempty from the worker.

When using PoW, geth begins mining on empty blocks before attempting to
select which transactions to include. This optimization is not needed,
as we require that every L2 block have exactly one transaction. This
commit disables this behavior an modifies the tests accordingly. The
test is also expanded to be stricter wrt to testing number of txs and
uncles on all blocks.

Slither github action fix and ignore database

proxyd: trigger release

node.js version 16 is currently the lts version
so this commit updates each of the dockerfiles to
use node version 16

ci: fix proxyd publish

Updates the github action to properly reference
the `proxyd` dockerfile. The logic is copied from
the canary publish github action.

feat: more accurate gas-oracle gas metering

Develop -> Master Release PR

Version Packages

Develop -> Master PR

fix: relayer docs + release

Convert the average block gas limit to a `uint64` in the
codebase instead of it being used as a `float64`.

Compute the gas used in an epoch based on the
actual amount of gas used instead of assuming
that the full block's worth of gas was used in
each block.

The message relayer is turned off by default,
mention how to turn it on in the docs.