feat(packaging): generate sourcemaps

[trotyl]

Closes #662
BREAKING CHANGE: umd file name simplified from 'ng-zorro-antd.js' to 'antd.js'

PR Checklist

Please check if your PR fulfills the following requirements:

• The commit message follows our guidelines: https://github.com/NG-ZORRO/ng-zorro-antd/blob/master/CONTRIBUTING.md#commit
• Tests for the changes have been added (for bug fixes / features)
• Docs have been added / updated (for bug fixes / features)

PR Type

What kind of change does this PR introduce?

[ ] Bugfix
[x] Feature
[ ] Code style update (formatting, local variables)
[ ] Refactoring (no functional changes, no api changes)
[x] Build related changes
[ ] CI related changes
[ ] Documentation content changes
[ ] Application (the showcase website) / infrastructure changes
[ ] Other... Please describe:

What is the current behavior?

Issue Number: closes #662

What is the new behavior?

Change summary:

• Redesign the build-process as mentioned in build: publish sourcemap in release #662;
• Rename publish folder esm15 -> esm2015 as per angular/angular@15e8d50;
• Rename index.xxx to antd.xxx to avoid potential barrel usage;
• Simplify umd file name in bundles folder from ng-zorro-antd.js to antd.js;
• Enable source-maps.

Does this PR introduce a breaking change?

[x] Yes
[ ] No

The file name of umd bundle changed from ng-zorro-antd.umd[.min].js to antd[.min].js, the prefix is unnecessary in file name.

Other information

[coveralls]

Coverage remained the same at 41.715% when pulling f6eda69 on trotyl:source-map into 9073bc8 on NG-ZORRO:master.

[trotyl]

Ready for review.

[vthinkxie]

why not keep the original name ng-zorro-antd.js, it may confuse the users that the same name with react version.

[trotyl]

Whoever use the umd file must specify the npm package name like:

• <script src="https://unpkg.com/ng-zorro-antd@0.6.2/bundles/antd.umd.js">
• require('ng-zorro-antd/bundles/antd.umd.js')

It will always be a duplication, isn't it?

[vthinkxie]

ok, that is fine.