feat: adapt iOS date string format

[sdjdd]

某些 iOS 设备可能不支持使用 yyyy-MM-ddTHH:mm:ssZ 格式的字符串创建 Date。

微信开发者工具在新版中加入了警告，每次用上述格式调用 Date 构造函数时就会在控制台打印一条日志，影响开发时的体验。

由于不方便在 adapters 中修改 AV 上面的方法，索性直接改写 AV._parseDate，也同时支持了 react-native 等平台。

$ node benchmark.js '2020-01-02T03:04:05.678Z' 10000000
new Date(dateString): 4.375s
new Date(Date.parse(dateString)): 4.687s

[codecov]

Codecov Report

Patch coverage: 100.00% and no project coverage change.

Comparison is base (676758d) 61.25% compared to head (0bebd4b) 61.25%.

Additional details and impacted files

@@           Coverage Diff           @@
##           master     #678   +/-   ##
=======================================
  Coverage   61.25%   61.25%           
=======================================
  Files          40       40           
  Lines        3479     3479           
=======================================
  Hits         2131     2131           
  Misses       1348     1348           

Files Changed	Coverage Δ
src/utils/index.js	98.52% <100.00%> (ø)

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