Don't use std::ignore for unused parameters

[ldrumm]

std::ignore seems to have been adopted as some sort of ersatz (void) cast or [[maybe_unused]] annotation on unused parameters. Since the following are true:

1. The behavior of std::ignore outside of std::tie is not formally specified;
2. C++ already has builtin ways to express ignorance of a value;
3. Compiling std::tie is much more expensive than using the builtin alternatives [1];
4. It's confusing to read;
5. It requires an extra header inclusion: I decided to simply omit the argument name in all cases where this is possible.

This is a mostly completely mechanical transformation, using the following script:

find unified-runtime -name "*.[ch]pp" \
  | xargs sed -i '/^\s*std::ignore\s*=\s*[a-zA-Z_][a-zA-Z0-9_]*;/d' \
  &&  git ls-files -m | parallel clang-tidy \
    '--checks="-*,misc-unused-parameters"' --fix --fix-errors -p build

Followed by manually introducting [[maybe_unused]] in NDEBUG blocks in a few places.

[1]: Both clang and gcc with libstdc++ and libc++ show similar slowdowns compiling the std::ignore vs void.
I didn't try with MSVC but I see no reason it wouldn't be similar

$ ipython3
In [1]: def ignore(n):
   ...:     ignores = 'std::ignore = x;\n' * n
   ...:     return f'''#include <tuple>\nint foo(int x) {{ {ignores} \n return x;}}'''
   ...:

In [2]: def void(n):
   ...:     voids = '(void)x;\n' * n
   ...:     return f'''int foo(int x) {{ {voids} \n return x;\n}}'''
   ...:

In [3]: with open("ignore.cpp", "w") as f:
   ...:     f.write(ignore(100000))
   ...:

In [4]: with open("voids.cpp", "w") as f:
   ...:     f.write(void(100000))
   ...:
$ time c++ -S voids.cpp
c++ -S voids.cpp  0.18s user 0.03s system 99% cpu 0.211 total
$ time c++ -S ignore.cpp
c++ -S ignore.cpp  4.50s user 0.34s system 99% cpu 4.836 total

[ldrumm]

ping @intel/dpcpp-nativecpu-reviewers, @intel/sycl-graphs-reviewers, @intel/unified-runtime-reviewers, and/or @intel/unified-runtime-reviewers-level-zero

[Bensuo]

Graphs/command-buffer changes LGTM

[hvdijk]

NativeCPU looks good, thanks.