Directory indexing for creating search database

[AasthaGupta]

Fixes issue: #70

Changes:

This will ease the process of updating search entries because now we
don't have to maintain a hard-coded database and a simple update in the
directory will be enough.

[AasthaGupta]

@AdiChat Please review it and let me know if any changes are required.

[AdiChat]

Generating metadata obj every time Quark is loaded may not be efficient.

Instead, you can create a script to generate the metadata (as you did) from a settings page setting.html. Users may trigger this manually. Also, moving the metadata from popup.js to a separate file will be a good design choice.

Kindly take a look into this and make appropriate changes. 👍

[AasthaGupta]

@AdiChat I have made the required changes. Please review it and let me know if any more changes are required.

[AasthaGupta]

@AdiChat any update on this?

[AasthaGupta]

@AdiChat I have updated the pull request.

• Now directory indexing will be done only once and stored in the local storage.Moreover, it will done in the background, so the extension can start without any delay.
• Added the option to Refresh under settings, to refresh the data.