feat: use inspector for heap profiles

[psx95]

For heap profiling, replaces the native C++ addon with calls to Node's inspector module. This uses the same V8::CpuProfiler under the hood but communicates over the chrome devtools protocol.

A similar PR has been raised to determine viability of using Node's inspector module for time profiling.

Testing

• Able to produce heap profiles which can be viewed using the pprof tool.
• All unit tests are passing.

Caveats

• Although no the stackDepth parameter to the heap profile is still preserved here to avoid breaking changes, this parameter is a no-op now. Stack depth will default to 128. This is based on the native source code of the V8 heap profiler.
• The memory usage number seem a bit off when compared to what was generated by the native C++ addon. There are images of flame graphs attached to highlight this difference.

Flame graph generated using the in-built inspector

Flame graph generated using the C++ addon

The graphs look similar, but there are differences, mostly due to the serializeHeapProfile task. When using the in-built inspector, this process takes about 1.55MB, while in the implementation that used C++ addon, this process took 0.81MB.

This accounts for most difference b/w the memory usage reported by the different profilers.

[conventional-commit-lint-gcf[bot]]

🤖 I detect that the PR title and the commit message differ and there's only one commit. To use the PR title for the commit history, you can use Github's automerge feature with squashing, or use automerge label. Good luck human!

-- conventional-commit-lint bot https://conventionalcommits.org/

[nolanmar511]

Kokoro system tests have failed with the following (suggesting that maybe the heap profile isn't being written out successfully any more):

+ pprof -filefunctions -top -nodecount=2 heap.pb.gz
+ grep 'busyLoop.*src/busybench.js'
+ tee
heap.pb.gz: parsing profile: empty input file
pprof: failed to fetch any source profiles