feat: Support @Func class method

[Lellansin]

depend on midwayjs/midway#448

[codecov-io]

Codecov Report

Merging #100 into master will decrease coverage by 0.01%.
The diff coverage is 85.71%.

@@            Coverage Diff             @@
##           master     #100      +/-   ##
==========================================
- Coverage   80.46%   80.44%   -0.02%     
==========================================
  Files          72       72              
  Lines        2564     2562       -2     
  Branches      242      255      +13     
==========================================
- Hits         2063     2061       -2     
  Misses        499      499              
  Partials        2        2              

Impacted Files	Coverage Δ
packages/faas/src/starter.ts	85.71% <85.71%> (-0.26%)	⬇️

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