Provides syntax highlighting and indentation for the P4 (P4_16-specification)
domain-specific programming language.

P4: https://p4.org/
P4_16-specification: https://p4.org/p4-spec/docs/P4-16-v1.2.0-spec.html

Inspiration comes from the gleam tree-sitter implementation
(https://github.com/gleam-lang/gleam-mode/blob/main/gleam-ts-mode.el)
and the tree-sitter-p4 grammar (https://github.com/oxidecomputer/tree-sitter-p4)