isTypedArray is implemented with `instanceof`, which does not work in jest (jestjs/jest#11864). Instead, use node's builtin `util.types.isUint8Array`, `util.types.isFloat32Array`, etc to perform this check.

Fixes tensorflow#7175.
This may also address tensorflow#7064, but it does not fix the root cause.

…exts

This change also removes platform_node_test from our normal glob of tests that run on the browser and node and places it in its own Bazel target.

Additionally, upgrade @types/node from 12 to 18 to allow importing `node:vm`.