Release rules_go v0.30.0 (bazel-contrib#3049)

Set RULES_GO_VERSION to 0.29.0 (bazel-contrib#2978)

Update Bazel and Ubuntu versions in CI configuration (bazel-contrib#2912

)

* Bazel 4.0.0 is now the minimum supported version.
  This is the LTS release.
* This is tested on Ubuntu 18.04, the oldest supported Ubuntu release.
* The latest version of Bazel is now tested on Ubuntu 20.04.

Set RULES_GO_VERSION to 0.27.0 (bazel-contrib#2851)

Add support for Go 1.16.1, 1.16.2, 1.15.9, 1.15.10 (bazel-contrib#2850)

Set RULES_GO_VERSION to 0.26.0 (bazel-contrib#2838)

Support Go 1.16 (bazel-contrib#2821)

Fixes bazel-contrib#2820

---

tests: partial cherry-pick of test change in bazel-contrib#2730

The Go 1.16 linker appears stricter about fingerprinting. This test no
longer works, but the behavior being tested was never supported.

Sync with the test on master, which always expects an error.

Support Go 1.15.8, 1.14.15 (bazel-contrib#2810)

Now testing with Bazel 3.7.2, the maximum supported version.
Compatibility with Bazel 4.0.0 was fixed in bazel-contrib#2683, but that broke
compatibility with 2.x.y, so it can't be backported to this branch.

Fixes bazel-contrib#2809

Support Go 1.15.7, 1.14.14 (bazel-contrib#2791)

Fixes bazel-contrib#2789

Test Go 1.16beta1 (bazel-contrib#2769)

* Set `GO111MODULE=off` in `go_info`
* Switched to Gazelle `v0.22.3` which also includes fixes.