GH-1003 Reimplement code snippets in UI

[WithoutAName25]

Fix #1003

[dzikoysk]

Hmm I see one thing that is kinda problematic. Bundle size is x2 bigger than it was before:

? 987 modules transformed.
rendering chunks...
build/frontend/reposilite-frontend/index.html                  1.70 KiB
build/frontend/reposilite-frontend/assets/index.395dd189.css   51.59 KiB / gzip: 9.33 KiB
build/frontend/reposilite-frontend/assets/index.512c4994.js    629.31 KiB / gzip: 216.66 KiB

After:

> Task :reposilite-frontend:buildFrontend
? 1186 modules transformed.
rendering chunks...
build/frontend/reposilite-frontend/index.html                  1.70 KiB
build/frontend/reposilite-frontend/assets/index.310f997f.css   54.10 KiB / gzip: 9.68 KiB
build/frontend/reposilite-frontend/assets/index.df79b065.js    1632.45 KiB / gzip: 505.17 KiB

Resource-wise we should probably just get rid of any highlight library 🤔

[WithoutAName25]

Maybe it would be a better option to don't use an editor library at all. It should be relatively easy to implement the code snippets manually. The highlighting could be "hardcoded" because the highlighted text doesn't change.

[dzikoysk]

Yeah, we've used highlighting library, because in the earlier version of 3.x we had configuration editor in Settings tab, but since we've replaced it with forms, it's no longer needed.

[WithoutAName25]

Main visual changes:

• no line numbers
• vertical scrolling instead of line wrapping

[dzikoysk]

Looks fine, thanks!