connect: enable configuring sidecar_task.name

connect: correctly handle missing sidecar_service task stanza

Before, the submitted jobspec for sidecar_task would pass
through 2 key validation steps - once for the subset specific
to connect sidecar task definitions, and once again for the set
of normal task definition where the task would actually get
unmarshalled.

The valid keys for the normal task definition did not include
"name", which is supposed to be configurable for the sidecar
task. To fix this, just eliminate the double validation step,
and instead pass-in the correct set of keys to validate against
to the one generic task parser.

Fixes #7680

Before, if the sidecar_service stanza of a connect enabled service
was missing, the job submission would cause a panic in the nomad
agent. Since the panic was happening in the API handler the agent
itself continued running, but this change will the condition more
gracefully.

By fixing the `Copy` method, the API handler now returns the proper
error.

$ nomad job run foo.nomad
Error submitting job: Unexpected response code: 500 (1 error occurred:
	* Task group api validation failed: 2 errors occurred:
	* Missing tasks for task group
	* Task group service validation failed: 1 error occurred:
	* Service[0] count-api validation failed: 1 error occurred:
	* Consul Connect must be native or use a sidecar service

Upgrade all golang.org/x packages

docs: fix link to envoy proxy documentation on consul site

Upgrade all golang.org/x packages to pick up fixes and improvements.
Some packages date back to 2018 and so much improvement happened since
then!

Prepare for 0.11.1 release

vendor: upgrade golang.org/x/net packages

changelog: add 0.11.0 release date.

golang.org/net packages are ancient - upgrading them to pick up
important fixes, e.g. https://go-review.googlesource.com/c/go/+/87298/

e2e: add a convenient creation script

Add a convenience Makefile for creating e2e environment for manual
debugging.

dev: Use go mod for managing hashicorp/go-msgpack

Use go mod for github.com/hashicorp/go-bindata/go-bindata and
github.com/elazarl/go-bindata-assetfs/go-bindata-assetfs but use
`@master` to pull the latest master.  These packages don't have release
tags so `@master` worksaround it.

tests: deflake some SetServer related tests

docs: update downloads+banner for 0.11.0 GA

docs: move rkt to external drivers

Co-Authored-By: Chris Baker <1675087+cgbaker@users.noreply.github.com>

docs: update changelog/upgrade for 0.11.0

Keep beta label for now.

Co-Authored-By: Buck Doyle <buck@hashicorp.com>

Co-Authored-By: Drew Bailey <2614075+drewbailey@users.noreply.github.com>

Adding `-trimpath` to builds removes the local working directory from
the goroutine stack traces, which makes our builds more reproducible
and doesn't leak information about our local development workstations
or CI environment.

Bumps [next](https://github.com/zeit/next.js) from 9.3.1 to 9.3.2.
- [Release notes](https://github.com/zeit/next.js/releases)
- [Commits](https://github.com/zeit/next.js/compare/v9.3.1...v9.3.2

)
Signed-off-by: dependabot[bot] <support@github.com>
Co-authored-by: dependabot[bot] <49699333+dependabot[bot]@users.noreply.github.com>

docs: add 0.11.0-rc1 to download page

Bumps [acorn](https://github.com/acornjs/acorn) from 5.7.3 to 5.7.4.
- [Release notes](https://github.com/acornjs/acorn/releases)
- [Commits](https://github.com/acornjs/acorn/compare/5.7.3...5.7.4

)
Signed-off-by: dependabot[bot] <support@github.com>
Co-authored-by: dependabot[bot] <49699333+dependabot[bot]@users.noreply.github.com>