Implement awk utility

[jgarzik]

Implement awk. Specification: https://pubs.opengroup.org/onlinepubs/9699919799/utilities/awk.html

Resources:

• https://www.raygard.net/awkdoc/ and https://github.com/raygard/wak/
• "one true awk" at https://github.com/onetrueawk/awk
• GNU awk at https://savannah.gnu.org/projects/gawk/
• AWK quick reference at https://www.grymoire.com/Unix/AwkRef.html