* Add license header to Makefile
* Unify tooling and build targets
Templatetize build and tooling targets.
Add the esc generator tooling.
* Refactor linting
* Update default targets
* Add dependabot-generate and fix dependabot-check
* Refactor tests
* Use upstream dbotconf
* Update ci test coverage workflow
* Revert to original redirection
* Test current and all sub packages
* Add vanity import check
* Update workflows
* Add vanity-import-fix and run it
* Update generation
* Update integration test cmds
* Remove compat testing for Go 1.18
* Fix modtime for zpages resources
* Add suggestion to vanity-import-check failure
* Add the toplevel module
So the go tooling stops throwing weird errors. Without that, running
make fails with the following message:
```
PATH="/…/.tools:${PATH}" go generate ./...
can't load package: package ./exporters/metric/dogstatsd: code in
directory /…/exporters/metric/dogstatsd expects import
"github.com/open-telemetry/opentelemetry-go-contrib/exporters/metric/dogstatsd"
can't load package: package ./plugins/sample/trace: code in directory
/…/plugins/sample/trace expects import
"github.com/open-telemetry/opentelemetry-go-contrib/plugins/sample/trace"
make: *** [Makefile:113: generate] Error 1
```
* Rename the module to use the vanity URL
The `go.opentelemetry.io/contrib` vanity URL is working now, so let's
officially switch to it.
Tyler Yahn
David Ashpole
Krzesimir Nowak