Checklist

• make -j4 test (UNIX), or vcbuild test nosign (Windows) passes
• commit message follows commit guidelines

Affected core subsystem(s)

src

Description of change

• Add an optional size param to node::Malloc() and node::Realloc() in calloc(3)-style and use proper overflow detection.
• Make the allocation methods templates so that they directly give the correct return type, removing a number of static_casts to the desired pointer types.
• Add shortcuts for the node::Malloc() + CHECK_NE(·, nullptr) combinations that often occur together in the codebase.
• Call v8::Isolate::GetCurrent()->LowMemoryNotification() when an allocation fails to give V8 a chance to clean up and return memory before retrying (and possibly giving up).

Any of the changes here can be left out but I believe that they all pretty much make sense to have.

CI: https://ci.nodejs.org/job/node-test-commit/4994/
CI: https://ci.nodejs.org/job/node-test-commit/4995/
CI: https://ci.nodejs.org/job/node-test-commit/4996/
CI: https://ci.nodejs.org/job/node-test-commit/4997/
CI: https://ci.nodejs.org/job/node-test-commit/5008/
CI: https://ci.nodejs.org/job/node-test-commit/5013/
CI: https://ci.nodejs.org/job/node-test-commit/5025/