Builds upon #1587.
Extract all symbol names that are not native to the current project and insert them into our own custom spell checking dictionary's "words" list.
The premise is that symbols that *are* native to our project should be spellchecked, but foreign symbols that constitute unrecognized dictionary words are presumably intentionally spelled that way.
# Convention
Manually-added words (i.e. for names in code that we've written for this project) will go into `.vscode/settings.json`.
The automatically generated word list from third-party packages goes into `cspell.json`.
# Usage
scripts/spellcheck/autopopulate-spellchecker.sh
