[#50][Pipelines] Simplify Pipelines to use module set-up

• None of the copying of sources around is necessary. I am not sure why was that necessary in the first place; I presume it was needed for an earlier version of Go.
• YottaDB Database set-up is not necessary. YDBGo handles that properly internally.
• Various invocations of $(go list ./... | grep -v /vendor/) are not necessary and result in output similar to this; now all removed.

ok  	lang.yottadb.com/go/yottadb	5.282s	coverage: 75.0% of statements
?   	lang.yottadb.com/go/yottadb/internal/israce	[no test files]
?   	lang.yottadb.com/go/yottadb/internal/test_helpers	[no test files]

• The artifacts for the unit test were kind of haphazard: the entire source was uploaded. I manually ran the tests in Dockerfile-test after .gitignore has been removed and determined which files are actually created. New condensed list will look like this:

/builds/shabiel/YDBGo/artifacts
/builds/shabiel/YDBGo/artifacts/m_routines
/builds/shabiel/YDBGo/artifacts/m_routines/helloworld1.m
/builds/shabiel/YDBGo/artifacts/m_routines/helloworld1.o
/builds/shabiel/YDBGo/artifacts/m_routines/CallMTStrTest.o
/builds/shabiel/YDBGo/artifacts/m_routines/TestMiscGoTimers.m
/builds/shabiel/YDBGo/artifacts/m_routines/helloworld99.o
/builds/shabiel/YDBGo/artifacts/m_routines/helloworld99.m
/builds/shabiel/YDBGo/artifacts/m_routines/helloworld2.m
/builds/shabiel/YDBGo/artifacts/m_routines/CallMTStrTest.m
/builds/shabiel/YDBGo/artifacts/m_routines/helloworld2.o
/builds/shabiel/YDBGo/artifacts/ydbgo3829126817
/builds/shabiel/YDBGo/artifacts/ydbgo3829126817/output.log
/builds/shabiel/YDBGo/artifacts/ydbgo3829126817/mumps.dat
/builds/shabiel/YDBGo/artifacts/ydbgo3829126817/mumps.gld

• Because of the removal of go list..., coverage code is simpler. I manually compared output of https://shabiel.gitlab.io/YDBGo/coverage.html vs https://yottadb.gitlab.io/Lang/YDBGo/coverage.html. It's identical; so the simpler code has the same output.
• Lint job should use the same global GOLANG_VERSION variable as the other jobs; no need for it to have a special one.
• None of the tests use the -short feature; so that invocation was removed. There is a potential application for it--replace the use of the environment variable YDB_GO_SKIP_TIMED_TESTS; but I won't about that for now.
• go build -i is deprecated per go command line.
• Added Visual Code Coverage to Gitlab pipeline (https://docs.gitlab.com/ee/ci/testing/test_coverage_visualization.html)
• Added Dockerfile-test to help debug pipeline problems locally.