op-batcher: Add metrics for pending L2 transaction data size

[trianglesphere]

Description

This adds metrics to track the size of pending blocks (rather than just the number).
It is expressed in a counter & a gauge. There is no new counter for the pending size
in channels because that counter already exists as the input_bytes metrics.

Note: This is based off of the op-batcher/v1.0.9-rc.1 tag.

[changeset-bot]

⚠️ No Changeset found

Latest commit: 6872908

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[codecov]

Codecov Report

Merging #5797 (361c892) into develop (df11f76) will decrease coverage by 2.69%.
The diff coverage is 14.81%.

Additional details and impacted files

@@             Coverage Diff             @@
##           develop    #5797      +/-   ##
===========================================
- Coverage    42.22%   39.54%   -2.69%     
===========================================
  Files          453      295     -158     
  Lines        29326    24692    -4634     
  Branches       877        0     -877     
===========================================
- Hits         12384     9764    -2620     
+ Misses       15985    14020    -1965     
+ Partials       957      908      -49     

Flag	Coverage Δ
bedrock-go-tests	39.54% <14.81%> (-0.03%)	⬇️
common-ts-tests	?
contracts-bedrock-tests	?
contracts-tests	?
core-utils-tests	?
dtl-tests	?
fault-detector-tests	?
sdk-tests	?

Flags with carried forward coverage won't be shown. Click here to find out more.

Impacted Files	Coverage Δ
op-batcher/metrics/metrics.go	0.00% <0.00%> (ø)
op-batcher/batcher/channel_manager.go	85.14% <100.00%> (+0.12%)	⬆️
op-batcher/metrics/noop.go	53.33% <100.00%> (+7.17%)	⬆️

... and 159 files with indirect coverage changes

[semgrep-app]

Semgrep found 1 todos_require_linear finding:

• op-wheel/engine/engine.go: L124

Please create a Linear ticket for this TODO.

_{Ignore this finding from todos_require_linear.}

Semgrep found 1 err-todo finding:

• op-wheel/engine/engine.go: L124

TODO in error handling code

_{Ignore this finding from err-todo.}