gre: refactor to allow using L1 and L2 simultaneously

[tmigone]

This PR adds support to GRE to allow using L1 and L2 chains simultaneously. This greatly simplifies interacting with the protocol.

Note that this is on hardhat's roadmap (see https://github.com/NomicFoundation/hardhat/issues/2797) but it's going to take a while before it's ready.

Relevant docs with more information:

• https://www.notion.so/edgeandnode/Multilayer-support-for-GRE-b2e41614822f453d89f47fa83afe9b95
• README.md file in gre folder

[abarmat]

Looking good

[codecov[bot]]

Codecov Report

Merging #682 (37cddd3) into dev (5232fd3) will not change coverage. The diff coverage is n/a.

@@           Coverage Diff           @@
##              dev     #682   +/-   ##
=======================================
  Coverage   90.35%   90.35%           
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  Files          35       35           
  Lines        1762     1762           
  Branches      296      296           
=======================================
  Hits         1592     1592           
  Misses        170      170           

Flag	Coverage Δ
unittests	90.35% <ø> (ø)

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[abarmat]

@tmigone what are the empty config files under gre/test/files, are those for existence tests?

[tmigone]

@tmigone what are the empty config files under gre/test/files, are those for existence tests?

Exactly. The tests are mainly to verify the plugin does path resolution correctly since there are a lot of cases to evaluate (and files need to exist to avoid erroring out). The contents of the files don't really matter as here we don't go that far so I figured it was better to leave them empty.

[abarmat]

Fixes GRT-8

[linear[bot]]

GRT-8 Multi-chain GRE