Disable copy-constructor and copy-assignment operations for the __future class

[SergeyKopienko]

Issue: #1776

What we change in this PR:

• remove copy constructor and copy assignment from the __future : to be closet for std::future implementation and to avoid multiple resource (`sycl::event') owners;
• change format of __future constructors: in all use cases we able to move sycl::event into the constructor instead of it's copy;
• change format of __future constructors: we pass std::tuple into constructor by const reference or as r-value;
• we change the semantic of __make_future functions: we declare it as static and rewrite it to avoid extra data copy and use data move if possible.

[danhoeflinger]

I would resist making direct changes until we have had the chance to discuss this holistically in the context of the asynchronous API discussion.
It is a public (experimental) API, so we may want to wait and then change it only a single time, in a deliberate way (perhaps in the context of productization).

[SergeyKopienko]

I would resist making direct changes until we have had the chance to discuss this holistically in the context of the asynchronous API discussion. It is a public (experimental) API, so we may want to wait and then change it only a single time, in a deliberate way (perhaps in the context of productization).

Unfortunately, not only (It is a public (experimental) API) : we widely using __future inside our code I would like to made it a little bit more optimal.