[SYCL] Add template template parameter support

[idubinov]

During the generation of the integration header, the forward declaration of the template template parameter did not printed.

In case of template template argument it is not necessary to call emitForwardClassDecls function recursively because of the maximum nesting level of template argument is equals two.

For example:

template <typename T> class Bar;
template <template <typename> class> class Baz;
template <template <template <typename> class> class T> class Foo;

The Baz is a template class.
The Baz<Bar> is a class.
The class Foo should be specialized with template class, not a class.
The correct specialization of template class Foo is Foo<Baz>.
The incorrect specialization of template class Foo is Foo<Baz<Bar>>. In this case template class Foo specialized by class Baz<Bar>, not a template class template <template <typename> class> class T as it should.
The maximum level of template nesting in specialization is 2.

The proposed fix prints forward declaration of Foo and Baz template classes into integration header. It's enough to prints declaration of template argument inside switch block.

Signed-off-by: idubinov [email protected]

[alexbatashev]

@idubinov should your PR address issues like #469?

[idubinov]

@alexbatashev ,
This PR does not solve issue #469.

[bader]

@idubinov, I'd like to make sure this change do not break SYCL implementation on Windows.
To do this, we need to pull #463.
Could you rebase your PR?

[idubinov]

@bader , @romanovvlad ,
PR rebased