This helps make the overall codebase consistent. `class_name()` in
`Kernel` is always `StringView`, but not elsewhere.
Additionally, this results in the `strlen` (which needs to be done
when printing or other operations) always being computed at
compile-time.
SPDX License Identifiers are a more compact / standardized
way of representing file license information.
See: https://spdx.dev/resources/use/#identifiers
This was done with the `ambr` search and replace tool.
ambr --no-parent-ignore --key-from-file --rep-from-file key.txt rep.txt *
