Add temporary "make" target for automated testing compatibility

Add temporary "make" target for automated testing compatibility

Utility "sslendpoints" and related packages make use of idiomatic Go
testing commands, i.e. go test [./...]. Thanks to Go Modules [1] nothing
else is needed to run internal tests for this tool.

Unfortunately it's not the case for all Go-based Integration tools. In
order to use a single automated verification script in CI additional
"make" target is required. It will provide temporary compatibility layer
with utilities setting up test environment on their own with "make test"
target.

This patch should be reverted upon removal of such cases (currently:
after dropping "../k8s/check" tool in favour of Aquasec solution).

[1] https://blog.golang.org/using-go-modules (see "Adding a dependency"
test execution explanation)

Issue-ID: INT-1498
Change-Id: I14c83f7f193c7688590366db988ff02c13c036a4
Signed-off-by: Pawel Wieczorek <p.wieczorek2@samsung.com>