This adds two new icons for browser context menu items "Close Other
Tabs" and "Download".
This adds existing icons where they were missing in context menu items.
Each of these strings would previously rely on StringView's char const*
constructor overload, which would call __builtin_strlen on the string.
Since we now have operator ""sv, we can replace these with much simpler
versions. This opens the door to being able to remove
StringView(char const*).
No functional changes.
Previously, Browser loaded icons from the disk every time an icon
was set. In addition to making more calls to the disk and decoding
more images, this makes error propagation impossible. This change
moves all icon loading to the start of the program.
