[v14.x backport] async_hooks: use new v8::Context PromiseHook API

[Qard]

This is a backport of #36394 to v14. There are some notable differences due to the older V8 version not having the newer ContextSlot enum with type-safe slots, but other than that is basically identical.

[nodejs-github-bot]

CI: https://ci.nodejs.org/job/node-test-pull-request/37955/

[Qard]

The GitHub Actions linux test is failing consistently with an error from buffers about something being used uninitialized. I don't see how that would be related to my changes. Is this a known issue in the v14.x-staging branch?

../src/node_buffer.cc:665:3: error: ‘offset’ may be used uninitialized in this function [-Werror=maybe-uninitialized]
  665 |   if (offset > ts_obj_length) {
      |   ^~
../src/node_buffer.cc:662:10: error: ‘max_length’ may be used uninitialized in this function [-Werror=maybe-uninitialized]
  662 |   size_t max_length;
      |          ^~~~~~~~~~
../src/node_buffer.cc: In function ‘void node::Buffer::{anonymous}::StringWrite(const v8::FunctionCallbackInfo<v8::Value>&) [with node::encoding encoding = node::ASCII]’:
../src/node_buffer.cc:665:3: error: ‘offset’ may be used uninitialized in this function [-Werror=maybe-uninitialized]
  665 |   if (offset > ts_obj_length) {
      |   ^~
../src/node_buffer.cc:662:10: error: ‘max_length’ may be used uninitialized in this function [-Werror=maybe-uninitialized]
  662 |   size_t max_length;
      |          ^~~~~~~~~~
../src/node_buffer.cc: In function ‘void node::Buffer::{anonymous}::StringWrite(const v8::FunctionCallbackInfo<v8::Value>&) [with node::encoding encoding = node::BASE64]’:
../src/node_buffer.cc:665:3: error: ‘offset’ may be used uninitialized in this function [-Werror=maybe-uninitialized]
  665 |   if (offset > ts_obj_length) {
      |   ^~
../src/node_buffer.cc: In function ‘void node::Buffer::{anonymous}::StringWrite(const v8::FunctionCallbackInfo<v8::Value>&) [with node::encoding encoding = node::BINARY]’:
../src/node_buffer.cc:665:3: error: ‘offset’ may be used uninitialized in this function [-Werror=maybe-uninitialized]
  665 |   if (offset > ts_obj_length) {
      |   ^~
../src/node_buffer.cc: In function ‘void node::Buffer::{anonymous}::StringWrite(const v8::FunctionCallbackInfo<v8::Value>&) [with node::encoding encoding = node::HEX]’:
../src/node_buffer.cc:665:3: error: ‘offset’ may be used uninitialized in this function [-Werror=maybe-uninitialized]
  665 |   if (offset > ts_obj_length) {
      |   ^~
../src/node_buffer.cc:662:10: error: ‘max_length’ may be used uninitialized in this function [-Werror=maybe-uninitialized]
  662 |   size_t max_length;
      |          ^~~~~~~~~~
../src/node_buffer.cc: In function ‘void node::Buffer::{anonymous}::StringWrite(const v8::FunctionCallbackInfo<v8::Value>&) [with node::encoding encoding = node::UCS2]’:
../src/node_buffer.cc:665:3: error: ‘offset’ may be used uninitialized in this function [-Werror=maybe-uninitialized]
  665 |   if (offset > ts_obj_length) {
      |   ^~

[Qard]

I see the latest commits on the branch have that failure too, I guess that is just getting ignored and PRs landing anyway. 🤷