This is a reland of crrev/c/3461263 with fix for crbug/1298289

This change includes commits:
0a242ce3e02a0e7d9c519601ed4fafb073fc98da Update vpython tests to use py3
fc06fd6815873bc40819476f88808b61ac447739 Change vpython spec search order
c6a2eb6ed31e0c815d7f28a42d7f12ee4cb47119 Update to latest virtualenv package.
038156fc1ffffa56b19c2c60674415eceb95f6bc New virtualenv to vpython.
ef44f81748a55c3aaf028ccfa2ee11876cee1285 Fix vpython filelock
275c4196540e1ca41384031b292ad0b89393a5dc Revert "Fix vpython filelock"
8aadd8b60a6d3801f62c7e5cebdfe3dc828a1546 Fix vpython filelock
43c99d88a24870240c9ca50d67dcfade40b516cc Use resolved path when searching spec
ffda9381bc01fd33e3c5a889e2ed374312c64ec6 Don't eval python symbol link on windows
30a66930f4037fff949d36c45b12f60a40ec524b Include GOARCH to verify cached environment
748dcd23529b6b138424914f1e6e265ed70d377b [vpython] Add period to log

Bug:1279621,1158462,1278132,1279684
Change-Id: I224d6abf6e106116da83aa2c34447e8601e48c67
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/tools/depot_tools/+/3530470Reviewed-by: Josip Sokcevic <sokcevic@google.com>
Commit-Queue: Chenlin Fan <fancl@chromium.org>