[SYCL] Improve kernel name diagnostics implementation

[srividya-sundaram]

This patch does the following changes in order to be conformant with the updated sycl kernel naming rules in SYCL 2020 spec:
Diagnoses kernel names,

  * declared within namespace 'std' (at any level)
    e.g., namespace std { namespace literals { class Whatever; } }
    h.single_task<std::literals::Whatever>([]() {});
  * declared within an anonymous namespace (at any level)
    e.g., namespace foo { namespace { class Whatever; } }
    h.single_task<foo::Whatever>([]() {});
  * declared within a function
    e.g., void foo() { struct S { int i; };
     h.single_task<S>([]() {} ); }
  * declared within another tag
    e.g., struct S { struct T { int i } t; };
    h.single_task<S::T>([]() {});

Adds new visitor functions:

VisitBuiltinType()

Updates existing diagnostics text.

Fixes #3103

[AaronBallman]

Heh, sorry, I didn't see the Draft tag until after I already did the review work. Sorry if I generated some noise for you!

[srividya-sundaram]

Heh, sorry, I didn't see the Draft tag until after I already did the review work. Sorry if I generated some noise for you!

Np. I tend to create a draft to check if my initial changes causes any tests to fail.
Thanks for the early feedback, I will address your comments.

[AaronBallman]

I may have missed it, but do we have sufficient existing test coverage for the incomplete struct cases and for the structs within structs cases?

[srividya-sundaram]

/summary:run

[AaronBallman]

LGTM aside from the commenting request.

[srividya-sundaram]

@kathywar I keep getting Err: Build failed with Error: hudson.AbortException: script returned exit code 255
Can you please take a look?

[kathywar]

I see this error in the verification run:

[srividya-sundaram]

Jenkins failure fixed by intel/llvm-test-suite#212
@bader Can you please merge this PR?

[bader]

Jenkins failure fixed by intel/llvm-test-suite#212
@bader Can you please merge this PR?

It must be approved by @intel/llvm-reviewers-runtime first.

[s-kanaev]

Other than the concern asked, the change looks good.

[s-kanaev]

RT test changes look good.

[srividya-sundaram]

ping @bader