Removes GK auth extension dependency

For upcoming premium features

Adds unit testing (just for the trie for now)

Consolidates to node-fetch 2.6.7 as Octokit requires v2

Adds image minify webpack config for debugging

Reorganizes local git support to exclude from web
Swaps sha1 usages to md5 to avoid needing sha1 on the web (md5 is required by Gravatar)
Avoids crypto-browserfy and imports md5.js directly
Uses platform crypto for random nonce strings