feat: do checksum if input addr is mixed case

[yqrashawn]

PORTAL-2879

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This change is 

[AngeliaQ]

Task linked: PORTAL-2879 接收支持 Checksum 地址并需要校验 Checksum 地址

[codecov]

Codecov Report

Merging #888 (c13fe16) into dev (e6a5953) will decrease coverage by 0.02%.
The diff coverage is 66.66%.

@@            Coverage Diff             @@
##              dev     #888      +/-   ##
==========================================
- Coverage   40.20%   40.17%   -0.03%     
==========================================
  Files         560      560              
  Lines       32813    32814       +1     
  Branches     1991     1885     -106     
==========================================
- Hits        13192    13183       -9     
- Misses      19437    19447      +10     
  Partials      184      184              

Flag	Coverage Δ
integrationtests	31.77% <66.66%> (-0.05%)	⬇️
unittests	27.39% <66.66%> (+0.01%)	⬆️

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Impacted Files	Coverage Δ
packages/account/index.js	98.05% <66.66%> (+3.94%)	⬆️
packages/rpc-engine/src/error.js	79.66% <0.00%> (-20.34%)	⬇️
packages/rpc-engine/middlewares/fetch.js	97.79% <0.00%> (-1.48%)	⬇️

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[zctocm]

Reviewed 4 of 4 files at r1, all commit messages.
Reviewable status: complete! all files reviewed, all discussions resolved (waiting on @yqrashawn)