Fully mute output info if quiet is set to true

[stephenlacy]

This fully mutes all startup messages if quiet is set.

What kind of change does this PR introduce?
This follows #970 and fully mutes all startup messages if quiet is set instead of just half.

Did you add or update the examples/?
No

Summary
Fully mutes all messages following webpack/webpack#1191 and #970.
This fixes issues on our build runners where stdout was outputted from the build even with quiet set.

Does this PR introduce a breaking change?
No

Other information

[jsf-clabot]

All committers have signed the CLA.

[codecov]

Codecov Report

Merging #999 into master will not change coverage.
The diff coverage is n/a.

@@           Coverage Diff           @@
##           master     #999   +/-   ##
=======================================
  Coverage   72.13%   72.13%           
=======================================
  Files           4        4           
  Lines         463      463           
  Branches      139      139           
=======================================
  Hits          334      334           
  Misses        129      129

---

Continue to review full report at Codecov.

Legend - Click here to learn more
Δ = absolute <relative> (impact), ø = not affected, ? = missing data
Powered by Codecov. Last update 8207238...07e802f. Read the comment docs.