[Deps] Find new TS linter

[joshua-goldstein]

Running npm install on current package gives unresolved peer dependency:

npm ERR! code ERESOLVE
npm ERR! ERESOLVE could not resolve
npm ERR! 
npm ERR! While resolving: [email protected]
npm ERR! Found: [email protected]
npm ERR! node_modules/tslint
npm ERR!   dev tslint@"^6.1.3" from the root project
npm ERR! 
npm ERR! Could not resolve dependency:
npm ERR! peer tslint@"^5.1.0" from [email protected]
npm ERR! node_modules/tslint-microsoft-contrib
npm ERR!   dev tslint-microsoft-contrib@"^6.2.0" from the root project
npm ERR! 
npm ERR! Conflicting peer dependency: [email protected]
npm ERR! node_modules/tslint
npm ERR!   peer tslint@"^5.1.0" from [email protected]
npm ERR!   node_modules/tslint-microsoft-contrib
npm ERR!     dev tslint-microsoft-contrib@"^6.2.0" from the root project
npm ERR! 
npm ERR! Fix the upstream dependency conflict, or retry
npm ERR! this command with --force or --legacy-peer-deps
npm ERR! to accept an incorrect (and potentially broken) dependency resolution.

Hence why we currently require npm install --legacy-peer-deps. This is because https://github.com/microsoft/tslint-microsoft-contrib is out of date and no longer maintained. We should switch to a more modern linter. Perhaps https://github.com/typescript-eslint/typescript-eslint.