[WIP] Convert rvgo's memory implementation to radix trie

[mininny]

No description provided.

[codecov]

Codecov Report

Attention: Patch coverage is 86.04651% with 36 lines in your changes missing coverage. Please review.

Project coverage is 73.08%. Comparing base (636210a) to head (89460e6).

Files with missing lines	Patch %	Lines
rvgo/fast/radix.go	87.98%	15 Missing and 13 partials ⚠️
rvgo/fast/page.go	55.55%	8 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##           master       #6      +/-   ##
==========================================
+ Coverage   72.30%   73.08%   +0.77%     
==========================================
  Files          16       17       +1     
  Lines        2723     2913     +190     
==========================================
+ Hits         1969     2129     +160     
- Misses        670      689      +19     
- Partials       84       95      +11     

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[protolambda]

You could add a slice as argument, to append the result to, and then return the updated slice header. Then you can allocate a slice with the capacity of the expected proof size once, and write to that in each proof level, to prevent allocations.

[mininny]

Closing in favor of ethereum-optimism#83