Vulkan: Fix sanitizers error with empty shader name

[pkpro]

In drivers/vulkan/rendering_device_vulkan.cpp:4815 on editor start compiled with following options:
dev_build=yes debug_symbols=yes optimize=debug use_ubsan=yes use_asan=yes use_lsan=yes use_msan=yes

Whenever you use a low level functionality for compute shaders the shader name is nullptr on editor start.
This is non critical, as the length of the shader name is 0, no actual copy happens, though the sanitizers report this as a runtime error.

[AThousandShips]

Please squash your commits into a single one, see here

[clayjohn]

Seems fine

[akien-mga]

Thanks for contributing. The fix looks correct, though check bruvzg's suggestion to make it better.

Aside from this, there are a number of Git issues that need to be handled:

• Your commit seems not to be linked to your GitHub account. See: Why are my commits linked to the wrong user? for more info.
• The commits should be squashed (see PR workflow).
• The resulting commit message should be improved. "memcpy into nullptr" isn't explicit enough about what is being fixed and where. This could apply to thousands of places in the codebase. Something like "Vulkan: Fix sanitizers error with empty shader name" would be good for example.

[akien-mga]

Note that you merged the remote into your branch, instead of rebasing, squashing, and amending the commit as I requested. So the PR now has 3 commits when it should be 1.

[clayjohn]

Looks good!

[akien-mga]

Thanks! And congrats for your first merged Godot contribution 🎉