fix: update dependencies of blockly-rtc so it builds

[maribethb]

Fixes #1087

Previously, npm install failed for most due to errors about having python installed. I expect for most of the team that happened because we were all forced to update macOS versions which removed python2. We were previously using an old version of sqlite that needed python2.

1. Updated the sqlite dependency to @vscode/sqlite3 which is just a more recently updated version of the package. Seems like the original package is not being updated on npm anymore. We needed a more recent version so that the node-gyp version wouldn't be hardcoded to v3.
2. Added a devDependency on node-gyp v9. Under the hood installing sqlite involves using node-gyp, and if you have it in the devDependencies it will use the version you specify. You need v9 for it to correctly handle the nuances of python on mac.

Note that if you are still having problems on mac and you get an error about not having Xcode dependencies installed, you need to install the Xcode command line tools. See also this doc if you are having problems: https://github.com/nodejs/node-gyp/blob/master/macOS_Catalina.md

Tested:

• npm install
• npm run start
• open /websocket.html in 2 tabs and functionality works