The installation instructions for all templates that require the `DEFAULT_GO_PACKAGES` taskfile variable point to the
"go-task" asset taskfile as its source. However, there was a redundant copy of this variable in the "check-go-task" asset
taskfile.

Maintaining two copies of this fairly complex asset is difficult, for no benefit in return, so it must be removed.

The templates for testing, linting, and formatting Go code work from a list of packages of the Go module which is output
from a `go list` command. Previously, it was only possible to get the packages of the module in the root of the repository.

Projects may contain multiple Go modules in subfolders of the repository. In order to support checks on these modules,
it's necessary to configure the commands to run from their path. This is passed to the task via the `GO_MODULE_PATH`
environment variable. If this variable is not defined, the default root module path is used as default, preserving the
previous task behavior.

The workflows use a job matrix to allow easy configuration for any number of module paths and a dedicated parallel job
for each module.

Because it may not be desirable to combine the code coverage data for all modules, a Codecov flag value can be defined
for each matrix job in the "Test Go" workflow. This workflow produces a two dimensional "operating system * module" job
matrix, running the tests for each module using all operating systems.