Switches all samples to use eslint 9 with flat configs. I've tried to migrate existing settings as much as possible. However our eslint configs were also inconsistent so I've tried to align these too
- Update @vscode/test-electron due to some bugs
- Update @vscode/test-cli for modern goodness
- vscode-dts -> @vscode/dts off of the deprecated name
- @types/node to 18 to match VS Code itself
This bumps the `@types/vscode` and `engines: vscode` on packages that were using very old versions. These old versions used a `vscode.d.ts` that didn't include proper link support. We've also made a number of fixes and improvements to `vscode.d.ts` that are useful to extension authors
Pick up latest eslint to avoid a nasty warning about using an unsupported version of TS
Also updates the eslint script to be more scoped on which files it checks
