cli commands (add, update) remove empty lines from package.json

[gkalpak]

Bug Report or Feature Request (mark with an x)

- [x] bug report -> please search issues before submitting
- [ ] feature request

Area

- [x] devkit
- [x] schematics

Versions

All

Repro steps

Some commands that modify package.json (e.g. ng update ... or ng add @angulatr/pwa (probably other ng add commands as well), remove an extra empty lines at the end of the file.

Desired functionality

Modifications in package.json should preserve empty lines. (Ideally, all whitespace should be preserved.)
Having an empty line at the end of each file is a common convention and removing such lines creates unnecessary noise in diffs. (Also note that other tools (e.g. yarn install) tend to add them back, which creates more unnecessary noise 😁)

[alexeagle]

This issue was moved to angular/angular-cli#12092