Reopen addImport with backward compatible addImports

[InsanusMokrassar]

Add API that require to use at least one name in imports in case of variadic syntax usage. The old behaviour have thrown an exception in runtime, but that one will not allow to use variadic syntax without at least one name

[Egorand]

Can you please explain what the motivation for this change is?

[InsanusMokrassar]

@Egorand you may look at this PR conversation for more info

[Egorand]

Not convinced that these changes are backwards compatible, CI should catch it - let's wait for the results. Also, can you please provide a more descriptive PR title that explains what the change does and why?

[Egorand]

Hey @InsanusMokrassar, looks like the code doesn't compile - would you be able to fix it?

[InsanusMokrassar]

Of course. Sorry for the delay, usually I am very busy, but I plan to fix it as soon as possible. Thanks for waiting :)

[Egorand]

Thanks & no pressure - just wanted to check if you're still planning to update the PR!