ui: collapse and expand files

[tanyunshi]

Refers to #182, #235 and #201: New feature for search quick navigation.

• Click on the button [expand all] or [collapse all] to expand/collapse all
• Click on a repository title to expand/collapse all the files of the repo
• Click on a file title to expand/collapse the file content

[bschlenk]

I've tried this out and I like it a lot. One change I'd make is to prevent expand/collapse when clicking the repository link itself. Currently if I click the link it takes me to a new page. When I come back to the search results, the matches for that repo are now collapsed.

[matheuzzy]

+1

[tanyunshi]

Closed as merged in #417.

Thank you for your wonderful work. Hound was my favorite tool for years. <3