Consolidate go modules to top level directory (#954)

* Consolidate go modules to top level directory

This allows developers who utilize things such as language server protocol to
easily resolve package level signatures across similar modules that make up the
project.

Fixes #557

Signed-off-by: Adam Stokes <[email protected]>

* Update go.mod

Co-authored-by: Manuel de la Peña <[email protected]>

* Remove e2e-testing modules from go.mod

This was causing some invalid import errors

Signed-off-by: Adam Stokes <[email protected]>

* add proper godog deps

Signed-off-by: Adam Stokes <[email protected]>

* Address issue with godog import

For now it is recommended to use the latest commit hash from go.elastic.co/apm
until the next official release is out. That release cleans up some internals in
that project making godog not a hard requirement when using apm as a dependency

Signed-off-by: Adam Stokes <[email protected]>

Co-authored-by: Manuel de la Peña <[email protected]>
(cherry picked from commit e0617f3)

# Conflicts:
#	cli/go.mod
#	cli/go.sum