feat: when osc visibility is set to always, apply osc margins to show menus above it

[Samillion]

Fixes: #302

• Use osc margins to show select menus and console above osc, when visibility=always
• Change z depth of osc to 1000 instead of -1
• When osc is visible, don't spam margins (verbose)
• Don't force hide osc with menus if osc visibility is set to always
• Remove unnecessary request_init() calls within osc_init()
• Apply osc margins within osc_init()
• Add cache_enabled() helper
• Don't use margins if osc is visible only temporarily
• Update chapter title to the current playing chapter
  • Since request_init() was used to update it (not sure why), it stopped working after its removal. Simply letting the content function handle it resolves the issue.
• Show cache_info tooltip on hover using the new cache helper function