Clean up index.html and move external CSS imports to index.js

All the external CSS imports now go in index.js for clarity.

For react-combo-search and its two peer deps (react-combo-select and react-datetime), the imports no longer point to local stylesheets but to the stylesheets available in node_modules. I've also re-added the two peer deps to package.json for ESLint and used a version number for react-combo-search instead of a git URL.

Since there were inconsistencies between the local styles and the node_modules styles, I went ahead and wrote my own overrides from scratch. The combo search component is used on the logbook. I've actually fixed a bug where the After radio button could not be selected.

BEFORE

AFTER