sequencer integration with L1 -> L2

[rahul-kothari]

Description

Fixes #529 (builds on #520 and #691)

• Archiver returns a list of pending message keys sorted by fees
• Archiver can also return a confirmed message given a key (useful for noir oracle calls)
• To implement the noir oracle call, aztec node has appropriate getter functions
• oracle call now fetches the appropriate message and the message index in the L1_TO_L2_MESSAGE_TREE
• Sequencer now calls the archiver to fetch pending messages to consume them in a l2 block (appropriate L1ToL2MessageSource interface was implemented)

Checklist:

• I have reviewed my diff in github, line by line.
• Every change is related to the PR description.
• I have linked this pull request to the issue(s) that it resolves.
• There are no unexpected formatting changes, superfluous debug logs, or commented-out code.
• The branch has been merged or rebased against the head of its merge target.
• I'm happy for the PR to be merged at the reviewer's next convenience.

[Maddiaa0]

Overall looks good!

[Maddiaa0]

lgtm