feat: upgrade rollup to 2

[PeachScript]

修改内容

• 升级 rollup 到 2.33.1
• 升级所有 rollup 官方插件，从 rollup-plugin-* 切换为 @rollup/plugin-*
• 切换 rollup-plugin-postcss-umi 为 rollup-plugin-postcss，以适配 rollup 2
• 更新所有 rollup 相关测试用例的期望产物内容（确认都是没有副作用的变更）
• 从代码和文档中移除 namedExports 配置项，rollup 2 已支持自动识别 exports，详见：feat(commonjs): set syntheticNamedExports for commonjs modules rollup/plugins#149
• 移除 getRollupConfig 中的 objectHashIgnoreUnknownHack，新的 TypeScript 插件不再需要使用这个属性来支持 async/await，详见：(fix): upgrade object-hash to support async/await syntax ezolenko/rollup-plugin-typescript2#203

close #269

[codecov]

Codecov Report

Merging #274 (e845f8b) into master (2dd0779) will increase coverage by 0.05%.
The diff coverage is 100.00%.

@@            Coverage Diff             @@
##           master     #274      +/-   ##
==========================================
+ Coverage   73.61%   73.67%   +0.05%     
==========================================
  Files          16       16              
  Lines         470      471       +1     
  Branches      162      163       +1     
==========================================
+ Hits          346      347       +1     
  Misses        123      123              
  Partials        1        1              

Impacted Files	Coverage Δ
packages/father-build/src/schema.ts	100.00% <ø> (ø)
packages/father-build/src/getRollupConfig.ts	97.70% <100.00%> (+0.02%)	⬆️

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[ycjcl868]

这个分支上发个 1.19.0-alpha.1 先试下

[ycjcl868]

ping @sorrycc ~

[PeachScript]

father-build@1.19.0-alpha.0 已发布，可用于测试 rolllup 2