test: Obsolete table argument in test:factory
suite: Factory now should be a function, not table
suite: Allow factories to be decorated.
test: Test for decorated test:factory
suite: Remove empty line, which violates guidelines
testing/decorators: Ensure decorator is transparent for return values
lua-nucleo/factory: Refactor arguments checking

Also replace custom typeassert to assert_is_table, for more useful diagnostic
testing/decorators: Improved diagnostic on failure
testing/decorators: Rename make_* to create_* according guidelines
test: Correct spelling