setup: Inital setup with Jest/Eslint/Prettier/TS/rollup

[hereismass]

Package setup with a few scripts: build/test/coverage/lint

• Hotjar object exported with basic init/isReady methods
• Jest added with babel to have it working with Typescript
• Rollup for bundling, with esm and commonjs targets
• typescript setup
• eslint setup to work with prettier

No CI or publish related work yet