This removes the direct dependency on sys/time.h from ElapsedTimer, and
makes the code a lot cleaner by using the helpers from AK::Time for
time math and getting the current timestamp.
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 *
