Improve isolation of test tags

[dataclouder]

• Moved functions used by more than one tag to a common area.
• Added a test to check tags isolation
• Added a command make tagverify to run the above test

$ make tagverify
==> Checking that code complies with gofmt requirements...
==> Running Tags Tests
=== RUN TagsTest
  --- PASS: TagsTest/api
  --- PASS: TagsTest/functional
  --- PASS: TagsTest/catalog
  --- PASS: TagsTest/vapp
  --- PASS: TagsTest/gateway
  --- PASS: TagsTest/network
  --- PASS: TagsTest/org
  --- PASS: TagsTest/query
  --- PASS: TagsTest/extnetwork
  --- PASS: TagsTest/task
  --- PASS: TagsTest/vm
  --- PASS: TagsTest/vdc
  --- PASS: TagsTest/system
  --- PASS: TagsTest/disk
  --- PASS: TagsTest/lb
  --- PASS: TagsTest/lbAppRule
  --- PASS: TagsTest/lbAppProfile
  --- PASS: TagsTest/lbServerPool
  --- PASS: TagsTest/lbServiceMonitor
  --- PASS: TagsTest/lbVirtualServer
  --- PASS: TagsTest/user
  --- PASS: TagsTest/search
  --- PASS: TagsTest/nsxv
  --- PASS: TagsTest/auth
  --- PASS: TagsTest/affinity
  --- PASS: TagsTest/ALL
--- PASS: TagsTest (49s)

[lvirbalas]

Small comment in-line, also do we need to amend TESTING.md?

[dataclouder]

Small comment in-line, also do we need to amend TESTING.md?

No need. The testing script will find the tags from api_vcd_test.go, thus enforcing in practice the directives we already have in TESTING.md

[lvirbalas]

Thanks, will now look forward to a make testrelease or alike 😄

[vbauzys]

LGTM