Add a test for SYCL_INTEL_local_memory extension

[sergey-semenov]

No description provided.

[sergey-semenov]

Depends on and checks the changes from intel/llvm#3329 and intel/llvm#3228

[Pennycook]

This looks great.

[Pennycook]

@jbrodman suggested that it might be a good idea to demonstrate some alternative ways to use the pointer, in case developers are basing their code on our tests, e.g.:

auto Ptr = group_local_memory_for_overwrite<int[WgSize]>(Item.get_group());

and

Foo& Ref = *group_local_memory(Item.get_group(), ...);

If all of these syntax options are functionally equivalent (as I think they are) then we might not need to actually test them, but it might still be worth adding a comment or two to let readers know other options are available.

[sergey-semenov]

@Pennycook Added a comment on this.

[vladimirlaz]

New directory is added. Could you please set correct code owner (in .github/CODEOWNERS)

[sergey-semenov]

Added myself as the code owner. @Pennycook Do you mind being set as the second code owner for the group local memory tests? (I this can be done as a separate PR, so that it does not block merging this one).

[Pennycook]

@Pennycook Do you mind being set as the second code owner for the group local memory tests?

Fine by me.