* Update to Go 1.16.2 for build/dev

* Update SDK version_base

* Update docker images

* make packages

* Revert "Saving and restoring the go cache was an experiment to reduce build times, but it worked too inconsistently. (#10493)"

This reverts commit 1e72bb1c.

* make ci-config

* ci: update default go image to use docker mirror

* bump to go1.15.11

- Previously there was version skew: 1.15.10 and 1.15.4 were in use.

* Update to go 1.15.6

* Just kidding, how about 1.15.7

* And the associated CI config

* Add changelog and update go version in more places

Name environments after their use case rather than their size.  We need fewer resources for remote-docker because all the heavy work happens in the remote-docker VMs which we can't configure.  Use a different env for race tests which are more resoure hungry. (#10492)

* ci: use docker mirror (source)

* ci: use docker mirror (gen)

* Update go version to 1.15.3

* Fix OU ordering for go1.15.x testing

* Fix CI version

* Update docker image

* Fix test

* packagespec upgrade -version 0.1.8
Co-authored-by: Sam Salisbury <samsalisbury@gmail.com>

* add packagespec build system

- The majority of changes in this commit are files generated
  by packagespec (everything in the packages-oss.lock directory).

* add .yamllint

* update to packagespec@fd54aea4

* ci: bust packagespec cache

- Change to packagespec results in package IDs that can use
  git tag refs, not just commit refs.

* update to packagepsec@5fc121d0

- This busts all caches, because of a change to the way we
  no longer traverse from tag refs to commit refs, due to
  the potential confusion this can cause.
- See https://github.com/hashicorp/packagespec/commit/fd54aea4827bb6cfd637c78a2ab6274111605330
  for the original change to packagespec necessitating this.

* update to packagespec@5e6c87b6

- This completes the change to allowing git tag refs
  to be used for source IDs, begun in f130b940a8fbe3e9398225b08ea1d63420bef7b6

* update to packagespec@4d3c9e8b

- This busts cache, needed to apply previous change.

* remove RELEASE_BUIL...