this seems to avoid some platform related optimizations that result
in integrity mismatches due to the resulting compressed output not
being byte for byte identical.

Tell `fetch` not to cache it's downloaded tarballs, leave that to us

Also see npm/cli#2976 for my first attempt & some discussions as to how
we got here.

Fix: #73
Fix: npm/cli#2160
Close: npm/cli#2976
Close: #74

EDIT(@isaacs): Updated to add test, allow make-fetch-happen to use the
cache, pipe into cache properly, and avoid cache double-writes.

PR-URL: #75
Credit: @mjsir911, @isaacs
Close: #75
Reviewed-by: @wraithgar, @mjsir911

Other manifest code paths go through read-package-json-fast, which end
up normalized through that package's `normalize` function.  Manifests
picked from the registry do not.  This adds consistency between the two.

fix(registry): normalize registry manifests

Fixes: npm/cli#3223

Fixes: npm/cli#2920

Fixes npm/cli#3300

update npmcli/git

…paring

fix: include all dep types when building for prepare

fix: do not set mtime when unpacking

fix: rethrow git pathspec errors from git operations on hosted services

BREAKING CHANGE: this moves our `engines` support and testing matrix
forward to node12 LTS and above.