Add renovate bot

[pokey]

• [x] #1281
• [ ] #1934
• [ ] Reopen #1090
• [ ] Enable auto-merge for renovate PRs
• [ ] Configure renovate to bump pre-commit, ensuring that it remains in lockstep with prettier etc in package.json
• [ ] Look at https://github.com/cursorless-dev/cursorless/issues/640#issuecomment-1299017494 to see if relevant here
• [ ] Force node.js version? Should match our @types/node version. Should figure out how it correlates to vscode node version. See also https://stackoverflow.com/a/29349773
• [ ] Pin vscode version to match engine version
• [x] Figure out how to reapply our patch https://github.com/cursorless-dev/cursorless/blob/de37ebf77834afad9a102cd5a4235886c72ece65/package.json#L49
• [ ] Look at https://github.com/typescript-language-server/typescript-language-server/blob/master/renovate.json for inspiration
• [ ] Run dedupe after lockfile update using pnpmDedupe post-update option