perf: plain and starknet etc use pub const string

[jujube]

cairo-vm/vm/src/types/layout.rs

Line 26 in 22a97dc

_name: String::from("plain"),

change to format

cairo-vm/vm/src/vm/runners/builtin_runner/mod.rs

Line 35 in 22a97dc

pub const OUTPUT_BUILTIN_NAME: &str = "output_builtin";

[Oppen]

Literals are functionally the same. In both cases, as long as the type remains String, you would be allocating a buffer and copying the string from the data segment or similar (depends on the platform). Some may consider one is cleaner, but other than that it is unlikely to have any observable difference.