feat: add teleportr Postgres backend

feat: update message-relayer to use the SDK

feat(core-utils): remove Watcher and injectL2Context

Replaces usage of injectL2Context with asL2Provider within the batch
submitter and the replica healthcheck service.

Removed duplicated utilities in data-transport-layer

maintenance: minor README updates

Removes all message relaying utilities found inside the message-relayer
package. All of these utilities are now present in the SDK. Also
re-implements the message-relayer service with the utilities found in
the SDK.

Version Packages

Develop -> Master

fix: skip an unreliable integration test

Skips the unreliable timestamp/blocknumber test which would often be off
by one or two. Creates an annoying habit of having to rerun the
integration tests until the test passes, which isn't how integration
tests should work.

go/proxyd: Handle nil responses better

fix: use correct token for label-requires-review

This check is the only one we have that uses PERSONAL_ACCESS_TOKEN,
perhaps it's expired or not present.

fix: make relayer work again

fix: remove extra space in BSS metric names

Fixes a bug where the relayer package was not correctly running the
start script since the start script updated recently.

feat: unify BSS metric name format, switch num_elements_per_batch to Summary

bss: properly set gas limit on clearing txs

feat: add LOG_TERMINAL flag, default to JSON

test(integration): replace watcher with sdk CrossChainMessenger

The histogram doesn't seem to render too well on Grafana, but the
batch_size_bytes one does. This commit modifies the
num_elements_per_batch to also use a Summary with the same buckets.

This commit:
 - Ensures each bss metric is prefixed by "batch_submitter_".
 - Ensures that Sequencer/Proposer name is made lowercase.
 - Ensures all units are present and positioned as a suffix.

This commit modifies the BSS to default to JSON logs, which are more
useful in production. This can be overridden by setting
LOG_TERMINAL to true for debugging locally.

feat(sdk): have SDK sort messages descending by bn

Fixes a bug where clearing txs are rejected on startup if the gas limit
is not set.

This was overlooked when
https://github.com/ethereum-optimism/optimism/pull/2107 was merged.

Has the SDK sort messages (deposits/withdrawals) descending by block
number. Makes for a better experience when presenting this data to
users.

feat(sdk): remove getTokenBridgeMessages function