Rollup refactor

[mateuszaaa]

• removed custom serialization
• removed JSON based serialization
• using eth compatible types for substrate <-> solidity hash calculation compatibility
• added test environment and adding unit tests for simplest scenarios
• added dedicated RPC/runtime api for query pending updates proofs

should be merge after #674

[codecov]

Codecov Report

Attention: 69 lines in your changes are missing coverage. Please review.

Comparison is base (71abd93) 48.39% compared to head (fc948e4) 51.36%.

Files	Patch %	Lines
pallets/rolldown/src/lib.rs	63.82%	51 Missing ⚠️
pallets/rolldown/rpc/src/lib.rs	0.00%	17 Missing ⚠️
node/src/rpc.rs	0.00%	1 Missing ⚠️

Additional details and impacted files

@@                  Coverage Diff                   @@
##           eth-rollup-develop     #687      +/-   ##
======================================================
+ Coverage               48.39%   51.36%   +2.96%     
======================================================
  Files                      42       44       +2     
  Lines                    7397     7307      -90     
======================================================
+ Hits                     3580     3753     +173     
+ Misses                   3817     3554     -263     

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