ZODB Components: Revert 'Allow to execute runUnitTest for bt5 Test Components' (dd6c5f7) to fix tests bootstrap.

The new syntax to load Tests Components is:
runUnitTest BT_TITLE:TEST_NAME

That commit was too adhoc as It was relying upon filesystem to load Tests
Components. Thus, it was not behaving like any other Components because versions
was not available and other Components were not importable as the site was not
already loaded at that point. At the end, it would have meant that a Test
Component ran through runUnitTest and Live Tests (in ERP5 itself) would have
behave differently.

Instead, use its ZODB version, which requires to:

1/ Install BT_TITLE dependencies and its test dependencies (new bt property to
   specify bt to be installed only for tests on a fresh instance) as given by
   bt5list files and by reusing ERP5TypeTestCase setUp() method.

2/ The site is loaded.

3/ Load the test by importing it like any other Components.

TODO-BEFORE-MERGE: Add comments.
ZODB Components: Test bootstrap is already done before even running the test.

Therefore, all Test Components are now ERP5TypeLiveTestCase. For backward
compatibility sake, just modify Test Component class bases to
ERP5TypeLiveTestCase, likewise runLiveTest.

This means that tests ran through runUnitTest and from Live Tests ERP5 UI would
behave exactly the same, contrary to the implementation before Test Components.
runUnitTest: Test the full ports range as some tests require Zope to listen on a port (testShaDir...).

With erp5testnode, many tests are running concurrently on the same machine and
only 3 ports were randomly tested before continuing and thus not listening to
any port. Moreover, checking the full range (500 ports) takes less than 1ms...
WIP