replace pkg/system Sequential funcs with moby/sys/sequential

[thaJeztah]

• depends on Integrate github.com/docker/docker/pkg/system Sequential utilities moby/sys#121
• relates to replace pkg/system Sequential funcs with moby/sys/sequential moby/moby#44051
• relates to replace sys Sequential funcs with moby/sys/sequential containerd/containerd#7334

Migrating these functions to allow them being shared between moby, docker/cli,
and containerd, and to allow using them without importing all of sys / system,
which (in containerd) also depends on hcsshim and more.

- A picture of a cute animal (not mandatory but encouraged)

[codecov-commenter]

Codecov Report

Merging #3755 (0e3d542) into master (d89b5db) will not change coverage.
The diff coverage is 80.00%.

@@ Coverage Diff @@## master #3755 +/- ##
=======================================
Coverage 59.14% 59.14% =======================================
Files 289 289 Lines 24680 24680 =======================================
Hits 14597 14597 Misses 9212 9212 Partials 871 871 

[thaJeztah]

For reviewers looking at the "+ LOC";

• most of the added lines from the new module is because it'll vendor another copy of the Apache LICENSE
• this should all be temporary; once other dependencies have migrated to this new package, the extra copy of these functions should go away

[sam-thibault]

LGTM

[thaJeztah]

Thx! Bringing this one in 👍