Add(concat): prefix and suffix options (fix #48)

[Riotpiaole]

Relevant issues & PRs

See #48.

Checklist

• [x] This affects the tests of the project.
• [x] I have updated the tests as needed.

[codecov-io]

Codecov Report

Merging #57 into master will decrease coverage by 0.03%. The diff coverage is 0%.

@@            Coverage Diff            @@
##           master     #57      +/-   ##
=========================================
- Coverage    7.57%   7.53%   -0.04%     
=========================================
  Files          61      61              
  Lines        2692    2706      +14     
=========================================
  Hits          204     204              
- Misses       2488    2502      +14

Impacted Files	Coverage Δ
packages/hopp-plugin-concat/dist/index.js	0% <0%> (ø)	:arrow_up:

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[Riotpiaole]

So what am i fixing next? @karimsa