feat: customize load in agent or in app

[chenzhq]

Checklist

• [ ] npm test passes
• [ ] tests and/or benchmarks are included
• [ ] documentation is changed or added
• [ ] commit message follows commit guidelines

Affected core subsystem(s)

Description of change

根据配置选择是在agent，还是app上初始化sequelize。

[codecov[bot]]

Codecov Report

Merging #88 into master will decrease coverage by 1.09%. The diff coverage is 75.00%.

@@            Coverage Diff             @@
##           master      #88      +/-   ##
==========================================
- Coverage   85.71%   84.61%   -1.10%     
==========================================
  Files           4        4              
  Lines          63       65       +2     
==========================================
+ Hits           54       55       +1     
- Misses          9       10       +1     

Impacted Files	Coverage Δ
config/config.default.js	100.00% <ø> (ø)
agent.js	66.66% <50.00%> (-33.34%)	:arrow_down:
app.js	100.00% <100.00%> (ø)

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[chenzhq]

这个可以 merge 发包吗

[JoweiBlog]

这个可以发个包么。🙏