Add watch(), del(), splice() to config

[xuchaoying]

• Please check if the PR fulfills these requirements

• The commit message follows our guidelines
• Tests for the changes have been added (for bug fixes / features)
• Docs have been added / updated (for bug fixes / features)

• What kind of change does this PR introduce? (Bug fix, feature, docs update, ...)

feature

• What is the related issue? (Use #issue_id to relate an open issue)

no

• Does this PR introduce a breaking change?

no

• Other information:

[codecov]

Codecov Report

Merging #110 into master will increase coverage by 0.08%.
The diff coverage is 100%.

@@            Coverage Diff             @@
##           master     #110      +/-   ##
==========================================
+ Coverage    91.9%   91.98%   +0.08%     
==========================================
  Files          44       44              
  Lines        1568     1584      +16     
==========================================
+ Hits         1441     1457      +16     
  Misses        127      127

Impacted Files	Coverage Δ
packages/svrx/lib/configure/plugin.js	100% <100%> (ø)	⬆️
packages/svrx/lib/configure/index.js	98.72% <100%> (+0.03%)	⬆️

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