META: start major release 8.0.0 with some breaking changes

[brody4hire]

• drop support for Node.js < 10
• drop support for Windows 8.1 & Windows Phone 8.1, as I proposed in PR #371
• use @cordova/eslint-config (issue #370)
• update eslint and other devDependencies
• hopefully drop use of Q
• consider better spawn implementation as discussed in cordova-common
• ideally phase out use of shelljs
• check for any outdated package dependencies such as semver
• consider any other possible cleanup