[SYCL] get_access and get_host access enabling

[iburyl]

This second patch finishes the implementation of SYCL_INTEL_accessor_simplification extension.

It adds:

• get_host_accessor to buffer
• adds overloads for get_access to enable deduction guide
• refactored test, as requested in this PR: [SYCL] Accessor tags, CTAD and host_accessor #1838
• updated deduction guides, based on limitations found via refactored tests

[iburyl]

@bader
Do you agree with such test decomposition?

I made two separate groups of tests, with focus on testing correct deduction for each available constructor:

• for host accessors
• for device accessors.

Each of them is independently run for:

• accessors constructors interfaces and
• buffer get_[host_]access interface.

Other cases, such as working, when wrapped into classes, or when id is passed to operator[], or when buffer has custom allocator etc. are left to original test, which is no longer focusing on deduction rules.

[sergey-semenov]

The changes LGTM except for a minor comment