feat: use viper

[colinlyguo]

based on this fix pr: #1502

[codecov-commenter]

Codecov Report

Attention: Patch coverage is 56.62651% with 36 lines in your changes missing coverage. Please review.

Project coverage is 51.51%. Comparing base (67c8392) to head (b6570a0).

Files	Patch %	Lines
rollup/internal/controller/relayer/l2_relayer.go	47.22%	14 Missing and 5 partials ⚠️
rollup/internal/config/config.go	68.29%	8 Missing and 5 partials ⚠️
rollup/internal/controller/relayer/l1_relayer.go	33.33%	3 Missing and 1 partial ⚠️

Additional details and impacted files

@@                         Coverage Diff                         @@
##           fix-override-config-private-key    #1505      +/-   ##
===================================================================
- Coverage                            51.60%   51.51%   -0.10%     
===================================================================
  Files                                  156      155       -1     
  Lines                                12789    12797       +8     
===================================================================
- Hits                                  6600     6592       -8     
- Misses                                5621     5632      +11     
- Partials                               568      573       +5     

Flag	Coverage Δ
rollup	55.37% <56.62%> (-0.29%)	⬇️

Flags with carried forward coverage won't be shown. Click here to find out more.

☔ View full report in Codecov by Sentry.
📢 Have feedback on the report? Share it here.

[yiweichi]

hey @colinlyguo, tested and works well. should we merge it?

[colinlyguo]

hey @colinlyguo, tested and works well. should we merge it?

sounds good. pls ping other reviewers to pass in your PR.