I have found an error running tests in Golang projects that use
submodules. This PR fixes the issue by accessing the directory before
running the test.

The `commons` in the image is a git submodule in a subfolder inside a
parent folder where the workspace is set.
Release Notes:
- Fixed Go tests not being able to run in case the package (and the
`go.mod`) was in a nested folder. Pre-defined Go tasks have been changed
to now run in the package's directory. That means `go test ./package
-run MyTest` will run in `./package` and execute `go test -run MyTest`.
Also, `go test ./...` will run in the package directory, not at the root
of the Zed project, which is a small breaking change. In case one wants
to run `go test ./...` from the root, one can spawn a manual task that
does this.

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Co-authored-by: Thorsten Ball <mrnugget@gmail.com>