The generate commands have been modified to take advantage of the new
functionality in Go 1.11 that allows `go run` to execute a package
instead of individual files.
This functionality combined with Go modules allows us to execute a
package directly out of our pinned dependencies rather than accidentally
picking up another binary outside of the build environment.
This also simplifies the Makefile because they no longer have to be
responsible for installing the correct tooling since the Go command
takes care of that logic. It also makes it so that the Makefiles with
file generation can now be invoked from their appropriate subdirectories
so they are contained within the directory itself rather than relying on
values in the top level Makefile.
It is now possible to generate all files within this project by using:
go generate ./...
Or the Makefile can continue to be used.
This commit also copies over the special copy of `tmpl` that the storage
engine uses within the influxdb repository. It was never copied over so
using `go generate` on these packages did not work.